Cod sursa(job #2592804)

Utilizator popashtefan10Popa Stefan popashtefan10 Data 2 aprilie 2020 13:32:35
Problema Flux maxim Scor 70
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.43 kb
#include <iostream>
#include <cstdio>
#include <vector>
#include <queue>

using namespace std;

const int NMAX = 1000;
const int INF = 1000000000;

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

bool bfs(int start) {
  for(int i = 1; i <= n; i++)
    uz[i] = false, from[i] = 0;
  q.push(start);

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

    for(int vec: v[nod])
      if(!uz[vec] && c[nod][vec] != f[nod][vec]) {
        from[vec] = nod;
        q.push(vec);
      }
  }
  return uz[n];
}

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 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);
  }

  while(bfs(1))
    for(int vec: v[n])
      if(uz[vec] && c[vec][n] != f[vec][n]) {
        from[n] = vec;
        update_flux();
      }
  printf("%d", flux);

  return 0;
}