Cod sursa(job #2065862)

Utilizator silviu982001Borsan Silviu silviu982001 Data 14 noiembrie 2017 13:22:24
Problema Flux maxim Scor 0
Compilator cpp Status done
Runda Arhiva educationala Marime 1.31 kb
#include <iostream>
#include <fstream>
#include <unordered_set>
#include <queue>
using namespace std;

int c[1000][1000];


int main()
{
	ifstream in;
	in.open("maxflow.in", ios::in);
	int n, m, u, v, source, dest;
	in >> n >> m;
	source = 0;
	dest = n - 1;
	for (int i = 0; i < m; i++)
	{
		in >> u >> v;
		in >> c[u - 1][v - 1];
	}
	in.close();
	unordered_set<int> visited;
	int parent[1000];
	long max_flow = 0;

	for (;;)
	{
		memset(parent, 0, sizeof(parent));
		parent[source] = -1;
		visited.clear();
		visited.insert(source);
		queue<int> q;
		q.push(source);
		visited.insert(source);

		while (!q.empty())
		{
			int nod = q.front();
			q.pop();
			for (int i = 0; i < n; i++)
				if (c[nod][i] > 0 && visited.find(i) == visited.end())
				{
					parent[i] = nod;
					visited.insert(i);
					q.push(i);
				}
		}

		if (visited.find(dest) == visited.end())
			break;

		int min_f = INT_MAX;
		for (v = dest; v != source; v = parent[v])
		{
			u = parent[v];
			if (c[u][v] < min_f)
				min_f = c[u][v];
		}

		max_flow = max_flow + min_f;

		for (v = dest; v != source; v = parent[v])
		{
			u = parent[v];
			c[u][v] = c[u][v] - min_f;
			c[v][u] = c[v][u] + min_f;
		}
	}

	ofstream out("maxflow.out", ios::out);
	out << max_flow;
	out.close();
	return 0;
}