Cod sursa(job #2742766)

Utilizator DragosC1Dragos DragosC1 Data 21 aprilie 2021 18:33:12
Problema Flux maxim Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.78 kb
#include <fstream>
#include <vector>
#include <iostream>
#include <queue>
using namespace std;

int n, m;
vector<int> a[1001];
int C[1001][1001], F[1001][1001];
bool viz[1001];
int t[1001];
int rez;

const int Inf = 1e9;

void read() {
    int i, x, y, cap;
    ifstream f("maxflow.in");
    f >> n >> m;
    for (i = 1; i <= m; i++) {
        f >> x >> y >> cap;
        a[x].emplace_back(y);
        a[y].emplace_back(x);
        C[x][y] += cap;
    }
    f.close();
}

queue<int> Q;
bool bfs() {
    int i, x, fiu;
    for (i = 1; i <= n; i++)
        viz[i] = 0;
    viz[1] = 1;
    Q.push(1);
    while (!Q.empty()) {
        x = Q.front();
        Q.pop();
        if (x == n) continue;
        for (i = 0; i < a[x].size(); i++) {
            fiu = a[x][i];
            if (viz[fiu] || C[x][fiu] == F[x][fiu]) continue;
            viz[fiu] = 1;
            Q.push(fiu);
            t[fiu] = x;
        }
    }
    return viz[n];
}

void solve() {
    int i, fiu, x, fmin;
    while (bfs()) {
        int i;
        for (i = 0; i < a[n].size(); i++) {
            fiu = a[n][i];
            if (!viz[fiu] || C[fiu][n] == F[fiu][n]) continue;
            t[n] = fiu;

            fmin = Inf;

            x = n;
            while (x > 1) {
                fmin = min(fmin, C[t[x]][x] - F[t[x]][x]);
                x = t[x];
            }

            if (fmin == 0) continue;

            x = n;
            while (x > 1) {
                F[t[x]][x] += fmin;
                F[x][t[x]] -= fmin;
                x = t[x];
            }

            rez += fmin;
        }
    }
}

void output() {
    ofstream g("maxflow.out");
    g << rez;
    g.close();
}

int main() {
    read(); 
    solve();
    output();
    return 0;
}