pku 1273 Drainage Ditches 最大流入门基础题

#include <iostream>#include <cstdio>#include <cstring>#include <queue>using namespace std;#define MAX_VALUE 0x7fffffffint map[201][201];int path[201]; //path[i]: 路径, 保存i点的前一节点path[i]int flow[201]; //flow[i]: 保存此节点的最大流int N, M;int bfs(){memset(path, -1, sizeof(path));queue<int> q;q.push(1);flow[1] = MAX_VALUE;while(!q.empty()){int v = q.front();q.pop();if(v == M)return flow[v];for(int i = 1; i <= M; ++i){if(i != v && path[i] == -1 && map[v][i]){path[i] = v;flow[i] = flow[v]>map[v][i]?map[v][i]:flow[v]; //寻找此路径上的最大流q.push(i);}}}return -1;}int edmonds_karp(){int max_flow = 0;int v, cur, pre;while ((v = bfs()) != -1) //寻找增广路径{max_flow += v;cur = M;while (cur != 1){pre = path[cur];map[pre][cur] -= v; //正向capicity减map[cur][pre] += v; //反向加capicitycur = pre;}}return max_flow;}int main(){while(scanf("%d%d", &N, &M) != EOF){int s, e, v;memset(map, 0, sizeof(map));for(int i = 0; i < N; ++i){scanf("%d%d%d", &s, &e, &v);map[s][e] += v;}printf("%d/n", edmonds_karp());}return 0;}