Cod sursa(job #1632372)

Utilizator howsiweiHow Si Wei howsiwei Data 6 martie 2016 05:46:23
Problema Flux maxim Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.21 kb
#include <iostream>
#include <cstdio>
#include <vector>
#include <queue>
#include <functional>
using namespace std;
const int oo = 0x1f1f1f1f;

int main() {
#ifdef INFOARENA
	freopen("maxflow.in", "r", stdin);
	freopen("maxflow.out", "w", stdout);
#endif
	cin.sync_with_stdio(false);
	int n, m;
	cin >> n >> m;
	vector<vector<int>> adjl(n);
	vector<vector<int>> C(n, vector<int>(n, 0));
	for (int i = 0; i < m; i++) {
		int u, v, c;
		cin >> u >> v >> c;
		u--, v--;
		if (C[u][v] == 0 && C[v][u] == 0) {
			adjl[u].push_back(v);
			adjl[v].push_back(u);
		}
		C[u][v] += c;
	}
	int s = 0, t = n-1;
	vector<int> d;
	function<int(int,int)> dfs = [&] (int u, int c) {
		if (u == t) return c;
		int fu = 0;
		for (int v: adjl[u]) if (d[u] > d[v] && C[u][v] > 0) {
			int f = dfs(v, min(c, C[u][v]));
			fu += f;
			c -= f;
			C[u][v] -= f;
			C[v][u] += f;
			if (c == 0) break;
		}
		if (c > 0) d[u] = n;
		return fu;
	};
	int mf = 0;
	while (true) {
		d.assign(n, n);
		d[t] = 0;
		queue<int> q;
		q.push(t);
		while (!q.empty()) {
			int v = q.front();
			q.pop();
			for (int u: adjl[v]) if (d[u] == n && C[u][v] > 0) {
				d[u] = d[v]+1;
				q.push(u);
			}
		}
		if (d[s] == n) break;
		mf += dfs(s, oo);
	}
	printf("%d\n", mf);
}