OJ-Problems-Source/HDOJ/4297_autoAC.cpp

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#pragma comment(linker, "/STACK:16777216")
#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <string.h>
#include <queue>
using namespace std;
const int maxn = 1000010;
struct node {
int be, ne, weight;
void init(int b, int e, int v) {
be = b;
ne = e;
weight = v;
}
};
int rmq[maxn * 2];
struct RMQ {
int lg[maxn + 1], minn[20][maxn + 1], n;
RMQ() {
lg[0] = -1;
for (int i = 1; i <= maxn; i++) {
lg[i] = ((i & (i - 1)) == 0) ? lg[i - 1] + 1 : lg[i - 1];
minn[0][i] = i;
}
}
void init(int n) {
this->n = n;
for (int i = 1; i <= lg[n]; i++)
for (int j = 1; j <= n + 1 - (1 << i); j++) {
int a = minn[i - 1][j];
int b = minn[i - 1][j + (1 << (i - 1))];
minn[i][j] = rmq[a] < rmq[b] ? a : b;
}
}
int getmin(int s, int t) {
if (s > t) {
int temp = t;
t = s;
s = temp;
}
int k = lg[t - s + 1];
int a = minn[k][s];
int b = minn[k][t - (1 << k) + 1];
if (rmq[a] < rmq[b])
return a;
else
return b;
}
} st;
int root[maxn];
struct LCA {
int n, len, E[maxn];
node buf[maxn * 2];
int F[maxn * 2], pos[maxn], cnt;
int dis[maxn];
void init(int n) {
this->n = n;
len = 0;
memset(E, -1, sizeof(E));
}
void addedge(int a, int b, int w) {
buf[len].init(b, E[a], w);
E[a] = len++;
buf[len].init(a, E[b], w);
E[b] = len++;
}
int query(int a, int b) {
int k = st.getmin(pos[a], pos[b]);
return F[k];
}
void dfs(int a, int lev) {
F[++cnt] = a;
rmq[cnt] = lev;
pos[a] = cnt;
for (int i = E[a]; i != -1; i = buf[i].ne) {
int b = buf[i].be;
if (pos[b] != -1)
continue;
dis[b] = dis[a] + buf[i].weight;
dfs(b, lev + 1);
F[++cnt] = a;
rmq[cnt] = lev;
}
}
void dfs2(int a, int r) {
root[a] = r;
for (int i = E[a]; i != -1; i = buf[i].ne)
if (root[buf[i].be] == -1)
dfs2(buf[i].be, r);
}
void solve(int root) {
cnt = 0;
memset(pos, -1, sizeof(pos));
memset(dis, 0, sizeof(dis));
dfs(root, 0);
st.init(2*n-1);
}
} lca;
int nxt[maxn],n;
int cc[maxn],pos[maxn],len[maxn],num;
int f[maxn];
int find(int x) {
if (x != f[x])
f[x] = find(f[x]);
return f[x];
}
void circle() {
for (int i = 1; i <= n; i++)
f[i] = i;
num = 0;
memset(cc, -1, sizeof(cc));
memset(pos, -1, sizeof(pos));
for (int i = 1; i <= n; i++) {
int a = find(i);
int b = find(nxt[i]);
if (a == b)
cc[i]=++num;
f[a] = b;
}
for (int i = 1; i <= n; i++)
if (cc[i] != -1) {
int k = nxt[i];
int cnt = 0;
pos[i] = ++cnt;
root[i] = i;
while (k != i) {
pos[k] =++cnt;
root[k]=k;
cc[k]=cc[i];
k=nxt[k];
}
len[cc[i]] = cnt;
}
}
int main() {
int m;
while (scanf("%d %d", &n, &m) != EOF) {
lca.init(n + 1);
memset(root, -1, sizeof(root));
for (int i = 1; i <= n; i++)
scanf("%d", nxt + i);
circle();
for (int i = 1; i <= n; i++)
if (root[i]!=i)
lca.addedge(nxt[i], i, 1);
for (int i = 1; i <= n; i++){
if (root[i] == i){
lca.dfs2(i,i);
lca.addedge(0, i, 0);
}
}
lca.solve(0);
int a, b;
while (m-- > 0) {
scanf("%d %d", &a, &b);
int p = lca.query(a, b);
if (p != 0)
printf("%d %d\n", (lca.dis[a] - lca.dis[p]), (lca.dis[b]-lca.dis[p]));
else {
int ra = root[a], rb = root[b];
if (cc[ra] != cc[rb])
printf("-1 -1\n");
else {
int cnt=len[cc[ra]];
int temp1 = lca.dis[a];
int temp2 = lca.dis[b];
if (pos[ra] < pos[rb])
temp1 += pos[rb] - pos[ra];
else
temp1 += (cnt - pos[ra] + pos[rb]);
int temp3 = lca.dis[a];
int temp4 = lca.dis[b];
if (pos[rb]<pos[ra])
temp4 += pos[ra]- pos[rb];
else
temp4 +=(cnt-pos[rb]+pos[ra]);
if (max(temp1, temp2) < max(temp3, temp4))
printf("%d %d\n", temp1, temp2);
if (max(temp1, temp2) > max(temp3, temp4))
printf("%d %d\n", temp3, temp4);
if (max(temp1, temp2) == max(temp3, temp4)) {
if (min(temp1, temp2) < min(temp3, temp4))
printf("%d %d\n", temp1, temp2);
if (min(temp1, temp2) > min(temp3, temp4))
printf("%d %d\n", temp3, temp4);
if (min(temp1,temp2)==min(temp3, temp4)) {
if (temp1>=temp2)
printf("%d %d\n",temp1,temp2);
else
printf("%d %d\n",temp3,temp4);
}
}
}
}
}
}
return 0;
}