Cod sursa(job #2592735)

Utilizator popashtefan10Popa Stefan popashtefan10 Data 2 aprilie 2020 11:21:34
Problema Flux maxim Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.52 kb
#include <iostream>
#include <cstdio>
#include <vector>
#include <queue>
#define NMAX 1000
#define MMAX 5000
#define INF 550000000

using namespace std;

bool dest, uz[NMAX + 5];
int n, m, flux;
int f[NMAX + 5][NMAX + 5], c[NMAX + 5][NMAX + 5];
int from[NMAX + 5], mincf[NMAX + 5];
vector<int> v[NMAX + 5];

void update_flux() {
  int minf = INF + 5;
  for(int i = n; from[i] != 0; i = from[i])
    minf = min(minf, c[from[i]][i] - f[from[i]][i]);
  if(!minf)
    return;
  flux += minf;
  for(int i = n; from[i] != 0; i = from[i]) {
    f[from[i]][i] += minf;
    f[i][from[i]] -= minf;
  }
}

int bfs(int start) {
  for(int i = 1; i <= n; i++)
    uz[i] = false;
  queue<int> q;
  q.push(start);

  while(!q.empty()) {
    int nod = q.front();
    q.pop();
    uz[nod] = true;
    if(nod == n)
      continue;

    for(int x: v[nod]) {
      if(c[nod][x] == f[nod][x] || uz[x])
        continue;
      from[x] = nod;
      uz[x] = true;
      q.push(x);
    }
  }
  return uz[n];
}

int main() {
  freopen("maxflow.in", "r", stdin);
  freopen("maxflow.out", "w", stdout);
  int x, y, z;

  scanf("%d %d", &n, &m);
  for(int i = 1; i <= m; i++) {
    scanf("%d %d %d", &x, &y, &z);
    c[x][y] = z;
    v[x].push_back(y);
    v[y].push_back(x);
  }

  mincf[0] = c[0][1] = INF + 5;
  while(bfs(1))
    for(int nod: v[n]) {
      if(!uz[nod] || c[nod][n] == f[nod][n])
        continue;
      from[n] = nod;
      update_flux();
    }

  printf("%d", flux);

  return 0;
}