Cod sursa(job #1614732)

Utilizator howsiweiHow Si Wei howsiwei Data 26 februarie 2016 08:05:46
Problema Flux maxim Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.14 kb
#include <iostream>
#include <cstdio>
#include <vector>
#include <queue>
using namespace std;

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>> adjm(n, vector<int>(n, 0));
	for (int i = 0; i < m; i++) {
		int u, v, c;
		cin >> u >> v >> c;
		u--, v--;
		if (adjm[u][v] == 0 && adjm[v][u] == 0) {
			adjl[u].push_back(v);
			adjl[v].push_back(u);
		}
		adjm[u][v] += c;
	}
	int s = 0, t = n-1;
	int flow = 0;
	while (true) {
		vector<int> p(n, -1);
		p[s] = -2;
		vector<int> pts;
		queue<int> q;
		q.push(s);
		while (!q.empty()) {
			int u = q.front();
			q.pop();
			for (int v: adjl[u]) if (p[v] == -1 && adjm[u][v] > 0) {
				if (v == t) pts.push_back(u);
				else p[v] = u, q.push(v);
			}
		}
		if (pts.empty()) break;
		for (int u: pts) {
			p[t] = u;
			int c = adjm[u][t];
			for (int v = u; v != s; v = p[v]) {
				c = min(c, adjm[p[v]][v]);
			}
			for (int v = t; v != s; v = p[v]) {
				adjm[p[v]][v] -= c;
				adjm[v][p[v]] += c;
			}
			flow += c;
		}
	}
	printf("%d\n", flow);
}