hdu 3549 网络流dinic板子题

网络流Dinic板子题

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#include <iostream>
#include <cstdio>
#include <cmath>
#include <string>
#include <cstring>
#include <algorithm>
#include <limits>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#define lowbit(x) ( x&(-x) )
#define INF 1e9+7
#define pi 3.141592653589793
#define e 2.718281828459045
using namespace std;
typedef long long ll;
const int maxN=1005;
int N,M;
int r[maxN][maxN], pre[maxN], flow[maxN][maxN];
int dis[maxN];
queue<int> q;
int bfs()
{
while(!q.empty())
q.pop();
memset(dis, -1, sizeof dis);
dis[1] = 0;
q.push(1);
while(!q.empty())
{
int u = q.front();
q.pop();
for (int i = 1; i <= N;i++)
{
if(flow[u][i]>0&&dis[i]==-1)
{
dis[i] = dis[u] + 1;
q.push(i);
}
}
}
return dis[N] != -1;
}
int dfs(int x,int remain)
{
if(remain==0||x==N)
return remain;
int k;
for (int i = 1; i <= N;i++)
{
if(flow[x][i]>0&&dis[i]==dis[x]+1&&(k=dfs(i,min(remain,flow[x][i]))))
{
flow[x][i] -= k;
flow[i][x] += k;
return k;
}
}
return 0;
}
int main()
{
int t;
scanf("%d", &t);
int cnt=1;
while(t--)
{
memset(flow, 0, sizeof flow);
scanf("%d%d", &N, &M);
for (int i = 0; i < M;i++)
{
int a, b, c;
scanf("%d%d%d", &a, &b, &c);
flow[a][b] += c;
}
int ans = 0;
int res;
while(bfs())
{
while(res=dfs(1,INF))
ans += res;
}
printf("Case %d: %dn",cnt++, ans);
}
}