Cod sursa(job #1980930)

Utilizator gorneanu.andreiFMI Gorneanu Andrei gorneanu.andrei Data 14 mai 2017 13:27:10
Problema Flux maxim Scor 0
Compilator cpp Status done
Runda Arhiva educationala Marime 1.97 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#define INF 0x3f3f3f3f
#define MAXN 1030
using namespace std;

vector<int> lista[MAXN];
int n, m;
bool vizitat[MAXN];
int tata[MAXN];
int flow[MAXN][MAXN], cap[MAXN][MAXN];

void read(){

    fstream f("maxflow.in",ios::in);
    int a, b, c, i, j;

    f >> n >> m;

    while(f >> a >> b >> c){
        lista[a].push_back(b);
        lista[b].push_back(a);
        cap[a][b] = cap[a][b] + c;
        flow[a][b] = cap[a][b];
    }
}

void set_vizitat(){

    for(int i = 1;i <= n; ++i)
        vizitat[i] = false;
}

int BFS(){

    set_vizitat();
    vizitat[1] = true;
    queue<int> q;
    q.push(1);

    while(!q.empty()){
        int nod = q.front();
        int len = lista[nod].size();
        q.pop();

        for(int i = 0;i < len; ++i)
            if(!vizitat[lista[nod][i]] && flow[nod][lista[nod][i]] > 0){
                tata[lista[nod][i]] = nod;
                vizitat[lista[nod][i]] = true;
                q.push(lista[nod][i]);
                if(lista[nod][i] == n)
                    return 1;
            }
    }

    return 0;
}

void solve(){

    int minim, total = 0, x;

    while(BFS()){
        int len = lista[n].size();

        for(int i = 0;i < len; ++i){

            tata[n] = x;

            x = n;
            minim = INF;
            for(x = n;x != 1;x = tata[x])
                minim = min(minim,flow[tata[x]][x]);


            x = n;
            for(x = n;x != 1; x = tata[x]){
                flow[tata[x]][x] = flow[tata[x]][x] - minim;
                flow[x][tata[x]] = flow[x][tata[x]] + minim;
            }

            flow[tata[n]][n] = flow[tata[n]][n] - minim;
            flow[n][tata[n]] = flow[n][tata[n]] + minim;

            total += minim;
            }
        }

    fstream g("maxflow.out",ios::out);
    g << total;
}

int main(){

    read();
    solve();
    return 0;
}