mirror of
https://github.com/Kiritow/OJ-Problems-Source.git
synced 2024-03-22 13:11:29 +08:00
98 lines
2.1 KiB
C++
98 lines
2.1 KiB
C++
#include <iostream>
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#include <cstdio>
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#include <cstring>
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#include <cmath>
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#include <set>
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#include <vector>
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#include <map>
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#include <queue>
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#include <set>
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#include <algorithm>
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#include <limits>
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using namespace std;
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typedef long long LL;
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const int MAXN=20000 + 10;
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const int INF = numeric_limits<int>::max();
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const LL LL_INF= numeric_limits<LL>::max();
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int bit[MAXN][MAXN/32+100];
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struct Edge {
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int to,next;
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Edge(){}
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Edge(int _to,int _next):to(_to),next(_next){}
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}e[MAXN*10],e2[MAXN*10];
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int head[MAXN],tot,du[MAXN];
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int head2[MAXN],tot2;
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int n,m;
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void init(){
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for(int i=1;i<=n;i++)head2[i]=head[i]=-1,du[i]=0;
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tot2=0;
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tot=0;
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}
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void AddEdge(int u,int v){
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e[tot]=Edge(v,head[u]);
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head[u]=tot++;
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}
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void AddEdge1(int u,int v){
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e2[tot2]=Edge(v,head2[u]);
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head2[u]=tot2++;
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}
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int que[MAXN],front,rear;
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void _or(int posi,int posj){
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for(int i=0;i<=n/32;i++)bit[posi][i]|=bit[posj][i];
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}
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void top_bfs(){
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front=rear=0;
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memset(bit,0,sizeof(bit));
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for(int i=1;i<=n;i++){
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bit[i][i/32]=(1<<(i%32));
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if(du[i]==0){
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que[front++]=i;
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--du[i];
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}
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}
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while(front!=rear){
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int u=que[rear++];
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for(int i=head[u];~i;i=e[i].next){
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int v=e[i].to;
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AddEdge1(v,u);
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if(--du[v]==0)que[front++]=v;
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}
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}
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}
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template <class T>
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void Rd(T &tmp){
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char ch;
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while((ch=getchar())&&!isdigit(ch));
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tmp=0;
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do {
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tmp=(tmp<<3)+(tmp<<1)+(ch^48);
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}while((ch=getchar())&&isdigit(ch));
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return ;
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}
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int main()
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{
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int T;
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Rd(T);
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while(T--){
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Rd(n),Rd(m);
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init();
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for(int i=0,x,y;i<m;i++){
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Rd(x),Rd(y);
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AddEdge(x,y);
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++du[y];
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}
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top_bfs();
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int ans=0;
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for(int i=0;i<front;i++){
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int u=que[i];
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for(int j=head2[u];~j;j=e2[j].next){
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int v=e2[j].to;
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if(bit[u][v/32]&(1<<(v%32)))++ans;
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_or(u,v);
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}
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}
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printf("%d\n",ans);
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}
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return 0;
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}
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