Cod sursa(job #2955990)

Utilizator StanCatalinStanCatalin StanCatalin Data 18 decembrie 2022 14:50:42
Problema Flux maxim Scor 10
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.57 kb
#include <iostream>
#include <vector>
#include <fstream>
#include <queue>
#include <algorithm>
#include <climits>

using namespace std;

ifstream in("maxflow.in");
ofstream out("maxflow.out");

const int dim = 1005;

int n,m, sursa, destinatie;
long long int graf_rezidual[dim][dim];
vector<int> vec[dim];
queue<int> q;
int viz[dim];
int tata[dim];

int BFS() {
    for (int i=1; i<=n; i++) {
        viz[i] = 0;
    }
    viz[sursa] = 1;
    q.push(sursa);
    tata[sursa] = -1;
    while (!q.empty()) {
        int x = q.front();
        q.pop();

        for (auto y:vec[x]) {
            if (graf_rezidual[x][y] > 0 && !viz[y]) {
                viz[y] = 1;
                tata[y] = x;
                q.push(y);
            }
        }
    }
    return viz[destinatie];
}

int main() {
    in >> n >> m;
    int x, y, c;
    sursa = 1;
    destinatie = n;
    while (m--) {
        in >> x >> y >> c;
        vec[x].push_back(y);
        vec[y].push_back(x);
        graf_rezidual[x][y] = c;
    }
    long long int maxflow = 0;
    long long int mini = LONG_LONG_MAX;
    while (BFS()) {

        for (auto y:vec[destinatie]) {
            mini = LONG_LONG_MAX;
            tata[destinatie] = y;
            for (int j = destinatie; j != sursa; j = tata[j]) {
                mini = min(mini, graf_rezidual[tata[j]][j]);
            }

            maxflow += mini;

            for (int j = destinatie; j != sursa; j = tata[j]) {
                graf_rezidual[tata[j]][j] -= mini;
                graf_rezidual[j][tata[j]] += mini;
            }
        }
    }

    out << maxflow;

    return 0;
}