107 lines
2.2 KiB
C++
107 lines
2.2 KiB
C++
#include <iostream>
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#include <cstdio>
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#include <vector>
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#include <algorithm>
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#include <cstring>
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using namespace std;
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const int maxn=55555;
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int dfn[maxn], low[maxn], stack[maxn], belong[maxn], visit[maxn], match[maxn];
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bool instack[maxn];
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int top, scnt, Index, n, m, T;
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vector<int>vt[maxn];
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struct Node
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{
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int u, v;
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}f[2*maxn];
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void Init_tarjan()
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{
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top=scnt=Index=0;
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for(int i=1; i<=n; i++) dfn[i]=low[i]=instack[i]=0;
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}
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void tarjan(int u)
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{
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stack[++top]=u;
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dfn[u]=low[u]=++Index;
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instack[u]=1;
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for(int i=0; i<vt[u].size(); i++)
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{
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int v=vt[u][i];
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if(!dfn[v])
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{
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tarjan(v);
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low[u]=min(low[u],low[v]);
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}
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else if(instack[v])
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{
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low[u]=min(low[u],dfn[v]);
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}
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}
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if(low[u]==dfn[u])
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{
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int v;
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scnt++;
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do
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{
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v=stack[top--];
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instack[v]=0;
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belong[v]=scnt;
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}
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while(u!=v);
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}
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}
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bool find(int u)
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{
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for(int i=0; i<vt[u].size(); i++)
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{
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int v=vt[u][i];
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if(!visit[v])
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{
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visit[v]=1;
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if(match[v]==-1||find(match[v]))
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{
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match[v]=u;
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return true;
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}
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}
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}
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return false;
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}
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int hungary()
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{
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int cnt=0;
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memset(match,-1,sizeof(match));
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for(int i=1; i<=scnt; i++)
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{
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for(int j=1; j<=scnt; j++) visit[j]=0;
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if(find(i)) cnt++;
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}
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return cnt;
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}
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int main()
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{
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cin >> T;
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while(T--)
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{
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cin >> n >> m;
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for(int i=0; i<=n; i++) vt[i].clear();
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for(int i=0; i<m; i++)
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{
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scanf("%d%d",&f[i].u,&f[i].v);
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vt[f[i].u].push_back(f[i].v);
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}
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Init_tarjan();
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for(int i=1; i<=n; i++)
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if(!dfn[i]) tarjan(i);
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for(int i=0; i<=n; i++) vt[i].clear();
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for(int i=0; i<m; i++)
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{
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int u=belong[f[i].u], v=belong[f[i].v];
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if(u==v) continue;
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vt[u].push_back(v);
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}
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int ans=hungary();
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cout << scnt-ans <<endl;
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}
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return 0;
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}
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