Cod sursa(job #2670424)

Utilizator Ioana_GaborGabor Ioana Ioana_Gabor Data 9 noiembrie 2020 21:08:16
Problema Flux maxim Scor 70
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.34 kb
#include <bits/stdc++.h>
#define NMAX 1000
#define MAXVAL (1LL<<31)-1;

using namespace std;

ifstream fi("maxflow.in");
ofstream fo("maxflow.out");

int n,m,x,y,z;
int sol,minf;
int capacity[NMAX+5][NMAX+5],flow[NMAX+5][NMAX+5];
int viz[NMAX+5],p[NMAX+5];
vector<int> G[NMAX+5];
queue<int> q;

bool bfs(){
    while(!q.empty()){
        q.pop();
    }
    for(int i=1;i<=n;i++){
        viz[i]=0;
    }
    q.push(1);
    viz[1]=1;
    int node,node2;
    while(!q.empty()){
        node=q.front();
        q.pop();
        for(int i=0;i<G[node].size();i++){
            node2=G[node][i];
            if(capacity[node][node2]-flow[node][node2]>0&&!viz[node2]){
                viz[node2]=1;
                p[node2]=node;
                q.push(node2);
                if(node2==n){
                    return true;
                }
            }
        }
    }
    return false;
}

int main(){
    fi>>n>>m;
    for(int i=1;i<=m;i++){
        fi>>x>>y>>z;
        G[x].push_back(y);
        G[y].push_back(x);
        capacity[x][y]+=z;
    }
    while(bfs()){
        minf=MAXVAL;
        for(int i=n;i!=1;i=p[i]){
            minf=min(minf,capacity[p[i]][i]-flow[p[i]][i]);
        }
        for(int i=n;i!=1;i=p[i]){
            flow[p[i]][i]+=minf;
            flow[i][p[i]]-=minf;
        }
        sol+=minf;
    }
    fo<<sol<<'\n';
    fi.close();
    fo.close();
}