Cod sursa(job #1556868)

Utilizator howsiweiHow Si Wei howsiwei Data 26 decembrie 2015 09:15:36
Problema Flux maxim Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.22 kb
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <vector>
#include <queue>
using namespace std;
const int oo = 1<<30;

vector<vector<int>> adjl;
vector<vector<int>> adjm;

int main() {
	freopen("maxflow.in", "r", stdin);
	freopen("maxflow.out", "w", stdout);
	int n, m;
	cin >> n >> m;
	adjl.resize(n);
	adjm.assign(n, vector<int>(n));
	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 flow = 0;
	while (true) {
		queue<int> q;
		q.push(0);
		vector<int> par(n);
		vector<bool> vis(n);
		vis[0] = true;
		while (!q.empty()) {
			int u = q.front();
			q.pop();
			for (int v: adjl[u]) {
				if (vis[v] || adjm[u][v] == 0) continue;
				vis[v] = true;
				if (v == n-1) continue;
				par[v] = u;
				q.push(v);
			}
		}
		if (!vis[n-1]) break;
		for (int u: adjl[n-1]) {
			par[n-1] = u;
			int c = oo;
			for (int v = n-1; v != 0; v = par[v]) {
				c = min(c, adjm[par[v]][v]);
				if (c == 0) break;
			}
			if (c == 0) continue;
			for (int v = n-1; v != 0; v = par[v]) {
				adjm[par[v]][v] -= c;
				adjm[v][par[v]] += c;
			}
			flow += c;
		}
	}
	printf("%d\n", flow);
}