题目链接

最小割

[题解](https://blog.csdn.net/wing_wuchen/article/details/77407413) 
#include <iostream>
#include <cstdio>
#include <cstring>
#include <map>
#include <vector>
#include <cmath>
#include <algorithm>
#include <queue>
#include <stack>

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;

const int Maxn = 50*50+10;
const int INF = 0x3f3f3f3f;
const int inf = 10000;
const long long LINF = 1e18;

struct Edge {
    int v, cap, flow, next;
} edge[Maxn*Maxn*10];

int h[Maxn], edge_cnt;
int indx[Maxn], deep[Maxn], qu[Maxn];

void add(int u, int v, int c) {
    edge[edge_cnt].v = v;
    edge[edge_cnt].cap = c;
    edge[edge_cnt].flow = 0;
    edge[edge_cnt].next = h[u];
    h[u] = edge_cnt++;

    edge[edge_cnt].v = u;
    edge[edge_cnt].cap = 0;
    edge[edge_cnt].flow = 0;
    edge[edge_cnt].next = h[v];
    h[v] = edge_cnt++;
}

bool bfs(int s, int t) {
    int head = 0, tail = 0;
    memset(deep, 0, sizeof(deep));
    deep[s] = 1; qu[tail++] = s;
    while(head < tail) {
        int u = qu[head++];
        for(int i = h[u]; i != -2; i = edge[i].next) {
            Edge &e = edge[i];
            if(deep[e.v] == 0 && e.cap-e.flow > 0) {
                deep[e.v] = deep[u]+1;
                qu[tail++] = e.v;
            }
        }
    }
    if(deep[t] > 0) return true;
    else return false;
}

int dfs(int cur, int t, int a) {
    if(cur == t || a == 0) return a;
    int flow = 0, f;
    if(indx[cur] == -1) indx[cur] = h[cur];
    for(int &i = indx[cur]; i != -2; i = edge[i].next) {
        Edge &e = edge[i];
        if(deep[e.v] == deep[cur]+1) {
            f = dfs(e.v, t, min(a, e.cap-e.flow));
            if(f > 0) {
                e.flow += f;
                edge[i^1].flow -= f;
                flow += f;
                a -= f;
                if(a == 0) break;
            }
        }
    }
    return flow;
}

void dinic(int s, int t, int n) {
    int ans = 0;
    while(bfs(s, t)) {
        memset(indx, -1, sizeof(indx));
        ans += dfs(s, t, INF);
    }
    ans -= n*inf;
    if(ans >= 0) printf("-1\n");
    else printf("%d\n", -ans);
}

int main(void)
{
	int T;
	scanf("%d", &T);
	while(T--) {
        int n, m, k;
        scanf("%d%d%d", &n, &m, &k);
        for(int i = 0; i < Maxn; ++i) h[i] = -2;
        edge_cnt = 0;
        int val;
        for(int i = 1; i <= n; ++i) {
            add(0, (i-1)*m+1, INF);
            for(int j = 2; j <= m+1; ++j) {
                scanf("%d", &val);
                if(j == m+1) {
                    add((i-1)*m+m, n*m+1, inf-val);
                } else {
                    add((i-1)*m+(j-1), (i-1)*m+j, inf-val);
                }
            }
        }
        int u, v;
        for(int i = 0; i < k; ++i) {
            scanf("%d%d%d", &u, &v, &val);
            for(int j = 1; j <= m; ++j) {
                int y = j-val;
                if(y < 1) add((u-1)*m+j, 0, INF);
                else if(y > m) add((u-1)*m+j, n*m+1, INF);
                else add((u-1)*m+j, (v-1)*m+y, INF);
            }
        }
        dinic(0, n*m+1, n);
	}
	return 0;
}