poj 1459 多源汇最大流

分析在这里

窝把原来的那个方法也写上好了，反正也差不多....

其实....还写了最高标号预流推进....................................就是这么蛋疼....然而在这道题目上来说，，这三种方法其实都一样。。。

code：

#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
#include<vector>
#include<string>
#include<queue>
#include<map>
#include<set>
#include<cmath>
#include<cstdlib>
using namespace std;

#define INF 0x3f3f3f3f
#define PI acos(-1.0)
#define mem(a, b) memset(a, b, sizeof(a))

typedef pair<int,int> pii;
typedef long long LL;
//------------------------------
const int maxn = 205;

int n,m;

struct Edge{
      int to, cap, rev;//终点 容量 反向边
      Edge(int to_ = 0, int cap_ = 0, int rev_ = 0){
            to = to_;
            cap = cap_;
            rev = rev_;
      }
};
vector<Edge> g[maxn];
int level[maxn];//顶点到源点的距离标号
int iter[maxn];

void add_Edge(int from, int to, int cap){
      Edge tmp1(to, cap, g[to].size());
      g[from].push_back(tmp1);
      Edge tmp2(from, 0, g[from].size()-1);
      g[to].push_back(tmp2);
}
void bfs(int s){
      memset(level, -1, sizeof(level));
      queue<int> q;
      level[s] = 0;
      q.push(s);
      while(!q.empty()){
            int v = q.front();
            q.pop();
            for(int i = 0; i < g[v].size(); i++){
                  Edge& e = g[v][i];
                  if(e.cap > 0 && level[e.to] < 0){
                  level[e.to] = level[v] + 1;
                  q.push(e.to);
                  }
            }
      }
}
int dfs(int v, int t, int f){
      if(v == t) return f;
      for(int& i = iter[v]; i < g[v].size(); i++){
            Edge& e = g[v][i];
            if(e.cap > 0 && level[v] < level[e.to]){
                  int d = dfs(e.to, t, min(e.cap, f));
                  if(d > 0){
                        e.cap -= d;
                        g[e.to][e.rev].cap += d;
                        return d;
                  }
            }
      }
      return 0;
}
int max_flow(int s, int t){
      int flow = 0;
      for(;;){
            bfs(s);
            if(level[t] < 0) return flow;
            memset(iter, 0, sizeof(iter));
            int f;
            while((f = dfs(s, t, INF)) > 0){
                  flow += f;
            }
      }
}
//------------------上面是最大流模板部分 正确----------------------
int np, nc;
void init(){
      for(int i = 0; i < maxn; i++) g[i].clear();
      int u, v, w;
      char ch;
      for(int i = 1; i <= m; i++){
            while(scanf("%c", &ch)){
                  if(ch == '(') break;
            }
            scanf("%d,%d%c%d",&u,&v,&ch,&w);
            add_Edge(u, v, w);
      }
      for(int i = 1; i <= np; i++){
            while(scanf("%c", &ch)){
                  if(ch == '(') break;
            }
            scanf("%d%c%d",&u, &ch, &w);
            add_Edge(n, u, w);
      }
      for(int i = 1; i <= nc; i++){
            while(scanf("%c", &ch)){
                  if(ch == '(') break;
            }
            scanf("%d%c%d",&v, &ch, &w);
            add_Edge(v, n+1, w);
      }
      int ans = max_flow(n, n+1);
      printf("%d\n",ans);
}
int main(){
      while(scanf("%d%d%d%d",&n,&np, &nc, &m) != EOF){
            init();
      }
      return 0;
}

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