371 lines
10 KiB
C++
371 lines
10 KiB
C++
#pragma comment(linker, "/STACK:102400000,102400000")
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#include<iostream>
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#include<vector>
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#include<algorithm>
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#include<cstdio>
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#include<queue>
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#include<stack>
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#include<string>
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#include<map>
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#include<set>
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#include<cmath>
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#include<cassert>
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#include<cstring>
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#include<iomanip>
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#include<ctime>
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using namespace std;
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#ifdef _WIN32
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typedef __int64 i64;
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#define out64 "%I64d\n"
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#define in64 "%I64d"
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#else
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typedef long long i64;
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#define out64 "%lld\n"
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#define in64 "%lld"
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#endif
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#define foreach(c,itr) for(__typeof((c).begin()) itr=(c).begin();itr!=(c).end();itr++)
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#define FOR(i,a,b) for( int i = (a) ; i <= (b) ; i ++)
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#define FF(i,a) for( int i = 0 ; i < (a) ; i ++)
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#define FFD(i,a,b) for( int i = (a) ; i >= (b) ; i --)
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#define S64(a) scanf(in64,&a)
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#define SS(a) scanf("%d",&a)
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#define LL(a) ((a)<<1)
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#define RR(a) (((a)<<1)+1)
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#define pb push_back
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#define pf push_front
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#define X first
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#define Y second
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#define CL(Q) while(!Q.empty())Q.pop()
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#define MM(name,what) memset(name,what,sizeof(name))
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#define MC(a,b) memcpy(a,b,sizeof(b))
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#define MAX(a,b) ((a)>(b)?(a):(b))
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#define MIN(a,b) ((a)<(b)?(a):(b))
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const int inf = 0x3f3f3f3f;
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const long long inf64 = 0x3f3f3f3f3f3f3f3fLL;
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const double oo = 10e9;
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const double eps = 10e-9;
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const double pi = acos(-1.0);
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const int maxn = 100111;
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const int maxlevel = 21;
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struct Node
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{
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int now;
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int to;
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int c;
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int tot;
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int ss;
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const bool operator < (const Node& cmp) const {
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return tot > cmp.tot;
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}
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};
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int all;
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int n, m;
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vector<Node>g[maxn];
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int t[maxn];
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int dep[maxn];
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int df;
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int dfn[maxn];
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int dfv[maxn * 2];
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int st[maxn * 2][maxlevel];
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int up[maxn][maxlevel];
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int dp[maxn]; //down sum
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int xtof[maxn];
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int ftox[maxn];
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int vis[maxn];
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int lg2[maxn*2];
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void dfs(int now)
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{
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vis[now] = true;
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int to;
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for (int i = 0; i < (int)g[now].size(); i++) {
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to = g[now][i].to;
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if (!vis[to]) {
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t[to] = now;
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dfs(to);
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}
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}
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}
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int treedp(int now)
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{
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int to,id;
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dp[now] = 0;
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for (int i = 0; i < (int)g[now].size(); i++) {
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to = g[now][i].to;
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if (to != t[now]) {
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int temp = treedp(to) + g[now][i].c;
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g[now][i].tot = temp;
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dp[now] += temp;
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}
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else {
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id = i;
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}
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}
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if (t[now] != -1) {
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g[now][id].tot = all - dp[now];
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}
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return dp[now];
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}
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void euler_circuit(int now ,int step)
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{
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dep[now] = step;
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dfn[now] = df;
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dfv[df++] = now;
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int to;
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for (int i = 0; i < (int)g[now].size(); i++) {
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to = g[now][i].to;
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if (to != t[now]) {
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euler_circuit(to,step+1);
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dfv[df++] = now;
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}
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}
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}
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void get_up_node()
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{
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for (int i = 1; i <= n; i++) {
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up[i][0] = t[i];
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}
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int to;
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for (int step = 1; step < maxlevel; step++) {
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for (int now = 1; now <= n; now++) {
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to = up[now][step - 1];
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if (to == -1) {
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up[now][step] = -1;
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}
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else {
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up[now][step] = up[to][step - 1];
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}
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}
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}
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}
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void sparse_table()
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{
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for (int i = 1; i < df; i++){
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st[i][0] = dep[dfv[i]];
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}
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int to;
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for (int step = 1; step <= lg2[n] + 1; step++){
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for (int now = 1; now < df; now++) {
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to = now + (1 << (step - 1));
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if (to < df){
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st[now][step] = min(st[now][step - 1], st[to][step - 1]);
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}
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else{
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st[now][step] = st[now][step - 1];
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}
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}
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}
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}
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void relation()
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{
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int to;
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for (int now = 1; now <= n; now++){
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for (int i = 0; i < (int)g[now].size(); i++){
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to = g[now][i].to;
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if (to == t[now]){
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xtof[now] = i;
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}
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else{
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ftox[to] = i;
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}
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}
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}
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}
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int rmq(int l,int r)
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{
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return min(st[l][lg2[r - l]], st[r - (1 << lg2[r - l])][lg2[r - l]] );
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}
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int calculate(int x,bool first,int id1,int id2=-1)
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{
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if (id2 != -1){
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if (id1 > id2){
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swap(id1, id2);
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}
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}
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int sum = g[x][0].ss;
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sum -= g[x][id1].tot;
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if (id2 != -1){
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sum -= g[x][id2].tot;
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}
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int size = (int)g[x].size() - 1;
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if (size >= 1){
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sum += g[x][1].ss;
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}
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int ans = g[x][0].ss;
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if (id1 % 2 ){
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if (id1 + 1 <= size){
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ans -= g[x][id1 + 1].ss;
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if (id1 + 2 <= size){
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ans += g[x][id1 + 2].ss;
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}
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}
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if (id2 != -1){
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if (id2 % 2){
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ans -= g[x][id2].ss;
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if (id2 + 1 <= size){
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ans += g[x][id2 + 1].ss;
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}
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}
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else{
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if (id2 + 1 <= size){
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ans -= g[x][id2 + 1].ss;
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if (id2 + 2 <= size){
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ans += g[x][id2 + 2].ss;
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}
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}
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}
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}
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}
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else{
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ans -= g[x][id1].ss;
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if (id1 + 1 <= size){
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ans += g[x][id1 + 1].ss;
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}
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if (id2 != -1){
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if (id2 % 2){
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ans -= g[x][id2].ss;
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if (id2 + 1 <= size){
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ans += g[x][id2 + 1].ss;
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}
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}
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else{
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if (id2 + 1 <= size){
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ans -= g[x][id2 + 1].ss;
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if (id2 + 2 <= size){
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ans += g[x][id2 + 2].ss;
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}
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}
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}
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}
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}
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if (first) return ans;
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else return sum - ans;
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}
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int go_up(int now, int x)
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{
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int step = 0;
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while (x) {
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if (x & 1) {
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now = up[now][step];
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}
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step++;
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x >>= 1;
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}
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return now;
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}
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int find(int a,int b)
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{
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int l = dfn[a];
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int r = dfn[b];
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if (l == r){
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return g[a][0].ss;
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}
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if (l > r){
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swap(l, r);
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}
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int lca = rmq(l, r + 1);
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if (dep[a] - lca + dep[b] - lca == 1){
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if (dep[a] == lca){
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return g[b][xtof[b]].tot + calculate(b, false, xtof[b]);
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}
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else if (dep[b] == lca){
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return g[b][ftox[a]].tot + calculate(b, false, ftox[a]);
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}
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}
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else if (dep[a] > dep[b]+1){
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int temp = dep[a] - dep[b];
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int mid = lca + temp / 2;
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int child = go_up(a, dep[a] - mid - 1);
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if (temp % 2){
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return g[t[child]][ftox[child]].tot + calculate(t[child], false, ftox[child], xtof[t[child]]);
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}
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else{
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return g[t[child]][ftox[child]].tot + calculate(t[child], true, ftox[child], xtof[t[child]]);
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}
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}
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else if (dep[a] == dep[b] + 1) {
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int ca = go_up(a, dep[a] - lca - 1);
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int cb = go_up(b, dep[b] - lca - 1);
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int meet = t[ca];
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return g[meet][ftox[ca]].tot + calculate(meet, false, ftox[ca], ftox[cb]);
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}
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else if (dep[a] < dep[b]){
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int temp = dep[b] - dep[a];
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int mid = lca + (temp + 1)/ 2;
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int child = go_up(b, dep[b] - mid - 1);
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if (temp % 2){
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return g[t[child]][xtof[t[child]]].tot + calculate(t[child], false, xtof[t[child]], ftox[child]);
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}
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else{
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return g[t[child]][xtof[t[child]]].tot + calculate(t[child], true, xtof[t[child]], ftox[child]);
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}
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}
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else if(dep[a] == dep[b]) {
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int ca = go_up(a, dep[a] - lca - 1);
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int cb = go_up(b, dep[b] - lca - 1);
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int meet = t[ca];
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return g[meet][ftox[ca]].tot + calculate(meet, true, ftox[ca], ftox[cb]);
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}
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assert(false);
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}
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void start()
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{
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for (int i = 1; i <= n; i++) {
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vis[i] = false;
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}
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t[0] = t[1] = -1;
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dfs(1);
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treedp(1);
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for (int now = 1; now <= n; now++) {
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sort(g[now].begin(), g[now].end());
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for (int i =(int) g[now].size() - 1; i >= 0; i--) {
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g[now][i].ss = g[now][i].tot;
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if (i + 3 <= (int)g[now].size()) {
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g[now][i].ss += g[now][i + 2].ss;
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}
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}
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}
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df = 1;
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euler_circuit(1, 0);
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get_up_node();
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sparse_table();
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relation();
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}
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int main()
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{
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for (int i = 0; i < maxlevel; i++){
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if ( (1<<i) < maxn*2)
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lg2[1 << i] = i;
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}
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for (int i = 3; i < maxn*2; i++) {
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if (!lg2[i]){
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lg2[i] = lg2[i - 1];
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}
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}
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int T;
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cin >> T;
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while (T--) {
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all = 0;
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cin >> n >> m;
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for (int i = 0; i <= n; i++){
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g[i].clear();
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}
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Node node;
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for (int i = 1; i <= n - 1; i++) {
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SS(node.now);
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SS(node.to);
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SS(node.c);
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g[node.now].push_back(node);
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swap(node.now, node.to);
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g[node.now].push_back(node);
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all += node.c;
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}
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start();
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int a, b;
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for (int i = 1; i <= m; i++){
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SS(a); SS(b);
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printf("%d\n", find(a, b));
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}
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}
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return 0;
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}
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