Dinic【模板】

struct Edge{
	int next, to;
	Edge(){};
	Edge(int next, int to): next(next), to(to){};
}edge[maxm*2];
int head[maxn], W[maxn], cnt;
void add(int u, int v, int w){
	edge[++cnt] = Edge(head[u], v);
	head[u] = cnt;
	W[cnt] = w;
}
int dfs(int u, int flow){	//u表示当前节点，flow表示当前流到x的残量
	if(u == ed)
		return flow;
	int tmp = 0;		//tmp表示u节点总共流出的流量
	for(int i=head[u]; ~i; i=edge[i].next){   //for(int& i=cur[u]; ~i; i=edge[i].next)当前弧优化
		int v = edge[i].to;
		if(dep[v]==dep[u]+1 && W[i]>0){
			int di = dfs(v, min(flow, W[i]);	//di表示当前边流出的流量
			W[i] -= di;
			W[i^1] += di;
			flow -= di;
			tmp += di;
			if(!flow) return tmp;	//流到u的流量流完了
		}
	}
	if(flow) dep[u] = -1;   //这一轮有残量，则下一轮不到u 
	return tmp;
}
bool bfs(){
	queue<int> Q;
	memset(dep, 0, sizeof(dep));
	Q.push(st);
	dep[st] = 1;
	while(!Q.empty()){
		int u = Q.front();
		Q.pop();
		for(int i=head[u]; ~i; i=edge[i].next){
			int v = edge[i].to;
			if(W[i]>0 && !dep[v]){
				dep[v] = dep[u]+1;
				Q.push(v);
			}
		}
	}
	if(dep[ed] == 0)
		return false;
	return true;
}

int dinic(){
	int ans;
	while(bfs()){
        //for(int i=1; i<=n; ++i)    当前弧优化（两行）
        //    cur[i] = head[i];
		while(int d=dfs(st, INF))
			ans += d;
		}
	}
	return ans;
}

poj 1459 网络流入门题

抄了假的模板，一直tle,当前弧优化后可A，改用另一种模板可A，此外注意输入

63ms

#include<cstdio>
#include<queue>
#include<cstring>
#include<algorithm>
#define mms(x) memset(x, 0, sizeof(x))
using namespace std;
const int maxn = 205, maxm = 5e4, INF = 1e9;

struct Edge{
	int nxt, to;
	Edge() {};
	Edge(int nxt, int to): nxt(nxt), to(to) {};
}edge[maxm];
int head[maxn], cnt, W[maxm], dep[maxn], cur[maxn];
int st, ed;
void add(int u, int v, int w){
	edge[++ cnt] = Edge(head[u], v);
	head[u] = cnt;
	W[cnt] = w;
}

bool bfs(){
	queue<int> q;
	mms(dep);
	dep[st] = 1;
	q.push(st);
	while(!q.empty()){
		int u = q.front();
		q.pop();
		for(int i=head[u]; ~i; i=edge[i].nxt){
			int v = edge[i].to;
			if(W[i]>0 && !dep[v]){
				dep[v] = dep[u]+1;
				q.push(v);
			}
//			printf("u:%d v:%d dep:%d\n", u, v, dep[v]); 
		}
	}
	if(!dep[ed])
		return false;
	return true;
}
int dfs(int u, int flow){
	if(u == ed)
		return flow;
	int tmp = 0;
	for(int& i=cur[u]; ~i; i=edge[i].nxt){
		int v = edge[i].to;
		if(dep[v] == dep[u]+1 && W[i]){
			int di = dfs(v, min(flow, W[i]));
			W[i] -= di;
			W[i^1] += di;
			flow -= di;
			tmp += di;
			if(!flow) return tmp;
		}
	}
	if(flow) dep[u] = -1;
	return tmp;
}
int Dinic(){
	int ans = 0;
	while(bfs()){
		for(int i=0; i<=ed; ++i)
			cur[i] = head[i];
		while(int d=dfs(st, INF))
			ans += d;
//		printf("#%d\n", ans);
	}
	return ans;
}
int main()
{
	int n, np, nc, m;
	while(~scanf("%d%d%d%d", &n, &np, &nc, &m)){
		memset(head, -1, sizeof(head));
		cnt = -1;    
		int u, v, w;
		char ch;
		for(int i=0; i<m; ++i){
			scanf(" (%d,%d)%d", &u, &v, &w);
			add(u, v, w);
			add(v, u, 0);
		}
		st = n;
		for(int i=0; i<np; ++i){
			scanf(" (%d)%d", &v, &w);
			add(st, v, w);
			add(v, st, 0);
		}
		ed = n+1;
		for(int i=0; i<nc; ++i){
			scanf(" (%d)%d", &u, &w);
			add(u, ed, w);
			add(ed, u, 0);
		}
		printf("%d\n", Dinic());
	}
	return 0;
}