Cod sursa(job #2322307)

Utilizator MoodyFaresFares Mohamad MoodyFares Data 17 ianuarie 2019 17:58:42
Problema Flux maxim Scor 20
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.31 kb
#include <cstdio>
#include <vector>
#include <queue>
#include <algorithm>

const int MAX_N = 1000;

std::vector<int> g[MAX_N];

int n;
int cap[MAX_N][MAX_N];
int flow[MAX_N][MAX_N];
bool viz[MAX_N];
int prev[MAX_N];
int minR;

bool bfs(int u = 0) {
  for (int i = 0; i < n; i++) {
    viz[i] = false;
    prev[i] = -1;
  }
  viz[u] = true;
  std::queue<int> q;
  q.push(u);
  while (!q.empty()) {
    u = q.front();
    q.pop();
    for (auto v : g[u]) {
      if (!viz[v] && flow[u][v] < cap[u][v]) {
        q.push(v);
        prev[v] = u;
        viz[v] = true;
        minR = std::min(minR, cap[u][v] - flow[u][v]);
      }
    }
  }
  return viz[n - 1];
}

int main() {
  freopen("maxflow.in", "r", stdin);
  freopen("maxflow.out", "w", stdout);
  
  int m;
  scanf("%d%d", &n, &m);
  for (int i = 0; i < m; i++) {
    int u, v, c;
    scanf("%d%d%d", &u, &v, &c);
    u--;
    v--;
    g[u].push_back(v);
    g[v].push_back(u);
    cap[u][v] = c;
  }
  minR = 110000;
  while (bfs()) {
    int u = n - 1;
    for (auto v : g[u]) {
      if (viz[v] && flow[v][u] < cap[v][u])
        prev[u] = v;
      while (u != 0) {
        flow[prev[u]][u] += minR;
        flow[u][prev[u]] -= minR;
        u = prev[u];
      }
    }
  }
  int ans = 0;
  for (auto v : g[n - 1])
    ans += flow[v][n - 1];
  printf("%d\n", ans);
  return 0;
}