Cod sursa(job #3032956)

Utilizator NuSuntRomanIspir Alexandru NuSuntRoman Data 23 martie 2023 10:23:10
Problema Flux maxim Scor 40
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.25 kb
#include <bits/stdc++.h>

const int NMAX = 5e5 + 5;

struct flowEdge {
    int u, v, cap;
};

int n, m, f[NMAX], t[NMAX];

std :: vector < flowEdge > edges;
std :: vector < int > G[NMAX];

std :: ifstream fin("maxflow.in");
std :: ofstream fout("maxflow.out");

void DFS(int node) {
    f[node] = true;

    for (int i = 0; i < G[node].size(); ++ i) {
        int u = G[node][i];

        if (f[edges[u].v] == false && edges[u].cap > 0) {
            t[edges[u].v] = u;

            DFS(edges[u].v);
        }
    }
}

int main() {
    fin >> n >> m;

    for (int i = 0, u, v, cap; i < m; ++ i) {
        fin >> u >> v >> cap;

        edges.push_back({u, v, cap});
        G[u].push_back(edges.size() - 1);

        edges.push_back({v, u, 0});
        G[v].push_back(edges.size() - 1);
    }

    int flow = 0;

    while (1) {
        for (int i = 0; i <= n; ++ i) {
            t[i] = -1;
            f[i] = false;
        }

        DFS(1);

        if (t[n] == -1)
            break;

        int x = n;

        while (t[x] != -1) {
            edges[t[x]].cap --;
            edges[t[x] ^ 1].cap ++;

            x = edges[t[x]].u;
        }

        ++ flow;
    }

    fout << flow;

    return 0;
}