Cod sursa(job #1718569)

Utilizator valiro21Valentin Rosca valiro21 Data 18 iunie 2016 12:26:04
Problema Flux maxim Scor 0
Compilator cpp Status done
Runda Arhiva educationala Marime 1.28 kb
#include <iostream>
#include <queue>
#include <climits>
#include <fstream>
#include <vector>

#define NMax 1002

using namespace std;

int n;
int c[NMax][NMax], f[NMax][NMax], p[NMax];
queue<int> q;
vector<int> v[NMax];

int bfs(int source) {
	for (int i = 1; i <= n; i++) {
		p[i] = -1;
	}
	p[source] = -2;
	int fl = INT_MAX;

	q.push(source);
	while (!q.empty()) {
		int nod = q.front();
		q.pop();

		for (int i = 0; i < v[nod].size (); i++) {
			int next_nod = v[nod][i];
			if (c[nod][next_nod] - f[nod][next_nod] > 0 && p[next_nod] == -1) {
				fl = min(fl, c[nod][next_nod] - f[nod][next_nod]);
				p[next_nod] = nod;
				q.push(next_nod);
			}
		}
	}

	return fl == INT_MAX ? 0 : fl;
}

int main() {
	ios_base::sync_with_stdio(false);
	ifstream cin("maxflow.in");
	ofstream cout("maxflow.in");

	int m, x, y, C;
	cin >> n >> m;
	for (int i = 0; i < m; i++) {
		cin >> x >> y >> C;
		c[x][y] = C;
		v[x].push_back(y);
		v[y].push_back(x);
	}

	int flux = 0, fl;
	int source = 1;
	int destination = n;

	while ((fl = bfs(source))) {
		flux += fl;
		int nod = destination;
		while (nod != source) {
			int prev_nod = p[nod];
			f[prev_nod][nod] += fl;
			f[nod][prev_nod] -= fl;
			nod = prev_nod;
		}
	}

	cout << flux;

	return 0;
}