poj1273

最新推荐文章于 2019-03-19 16:31:03 发布

sunshine945

最新推荐文章于 2019-03-19 16:31:03 发布

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分类专栏： poj

本文链接：https://blog.youkuaiyun.com/sunshine_zqq/article/details/9794337

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#include<cstdio>
#include<cstring>
#define MAXM 205
#define INF 2000000005
struct Arc_Infor{
    int c, f;
};
Arc_Infor Edge[MAXM][MAXM];
int flag[MAXM], pre[MAXM], change[MAXM];
int que[MAXM];
int N, M;

void Ford() {
    while(1) {
        memset(flag, -1, sizeof(flag));
        memset(pre, -1, sizeof(pre));
        memset(change, 0, sizeof(change));
        flag[1] = 0;
        change[1] = INF;
        int front = 0, rear = 0;
        que[rear ++] = 1;
        while(front < rear) {
            int v = que[front];
            front ++;
            if(flag[M] != -1) {
                break;
            }
            for(int i = 1; i <= M; ++ i) {
                if(Edge[v][i].c - Edge[v][i].f != 0 && flag[i] == -1) {
                    flag[i] = 0;
                    pre[i] = v;
                    change[i] = change[v] < Edge[v][i].c - Edge[v][i].f ? change[v] : Edge[v][i].c - Edge[v][i].f;
                    que[rear ++] = i;
                }
            }
            flag[v] = 1;
        }
        if(flag[M] == -1 || change[M] == 0) {
            break;
        }
        int k1 = M, k2 = pre[M];
        while(1) {
            Edge[k2][k1].f += change[M];
            Edge[k1][k2].f = - Edge[k2][k1].f;
            if(k2 == 1) {
                break;
            }
            k1 = k2, k2 = pre[k1];
        }
    }
    int max_flow = 0;
    for(int i = 1; i < M; ++ i) {
        max_flow += Edge[i][M].f;
    }
    printf("%d\n", max_flow);
}

int main() {
    freopen("poj1273.txt", "r", stdin);
    int a, b, c;
    while(scanf("%d%d", &N, &M) != EOF) {
        for(int i = 1; i <= N; ++ i) {
            for(int j = 1; j <= N; ++ j) {
                Edge[i][j].c = Edge[i][j].f = 0;
            }
        }
        while(N --) {
            scanf("%d%d%d", &a, &b, &c);
            Edge[a][b].c += c;
        }
        Ford();
    }
    return 0;
}