dinic当前弧优化板子

本文主要是介绍dinic当前弧优化板子，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

洛谷的板题https://www.luogu.org/problemnew/show/P3376

#include <cstdio>
#include <cstring>
#include <queue>
#include <algorithm>using namespace std;const int MAX = (1ll << 31) - 1;long long read(){long long x = 0; long long zf = 1; char ch = ' ';while (ch != '-' && (ch < '0' || ch > '9')) ch = getchar();if (ch == '-') zf = -1, ch = getchar();while (ch >= '0' && ch <= '9') x = x * 10 + ch - '0', ch = getchar(); return x * zf;
}const int NN=510;
const int MM=NN*NN;
struct Edge{int to;long long dis;
} edges[MM<<1];vector <int> con[NN];int cur[NN];
int edge_num=-1;
int n, m, s, t;void addEdge2(int from, int to, int dis){edges[++edge_num].to = to;edges[edge_num].dis = dis;con[from].push_back(edge_num);
}void addEdge(int from, int to, int dis){addEdge2(from, to, dis), addEdge2(to, from, 0);
}int d[NN];long long DFS(int u, long long flow){if (u == t) return flow;long long _flow = 0, __flow;int up=con[u].size();for (int i = cur[u]; i<up ; i++){int c_e=con[u][i];int v = edges[c_e].to;if (d[v] == d[u] + 1 && edges[c_e].dis > 0){__flow = DFS(v, min(flow, edges[c_e].dis));flow -= __flow;edges[c_e].dis -= __flow;_flow += __flow;edges[c_e^1].dis += __flow;if (!flow)break;}}if (!_flow) d[u] = -1;return _flow;
}bool BFS(){memset(d, -1, sizeof(d));queue<int> que; que.push(s);d[s] = 0; int u, _new;while (!que.empty()){u = que.front(), que.pop();int up=con[u].size();for (int i = 0; i<up; i++){int c_e=con[u][i];_new = edges[c_e].to;if (d[_new] == -1 && edges[c_e].dis > 0){d[_new] = d[u] + 1;que.push(_new);}}}return (d[t] != -1);
}long long dinic(){long long max_flow = 0;while (BFS()){for (int i = 1; i <= n; ++i) cur[i] = 0;max_flow += DFS(s, MAX);}return max_flow;
}
int main(){n = read(), m = read(), s = read(), t = read();//点数边数源点汇点for (int i = 0; i < m; i++){int u = read(), v = read(), w = read();//边流量addEdge(u, v, w);}long long ans=dinic();printf("%lld\n",ans);return 0;
}