Cod sursa(job #1980766)

Utilizator gorneanu.andreiFMI Gorneanu Andrei gorneanu.andrei Data 13 mai 2017 22:25:55
Problema Flux maxim Scor 60
Compilator cpp Status done
Runda Arhiva educationala Marime 2.2 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#define MAXN 1005
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;

    for(i = 1;i <= n; ++i)
        for(j = 1;j <= n; ++j)
            cap[i][j] = flow[i][j] = 0;

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

    for(int i = 1;i <= n; ++i){
        vizitat[i] = false;
        tata[i] = 0;
    }
}

int BFS(){

    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]] && cap[nod][lista[nod][i]] != flow[nod][lista[nod][i]]){
                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 set_vizitat(){

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

void solve(){

    int minim, total = 0, x;

    for (total = 0; BFS();){
        int len = lista[n].size();

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

            x = lista[n][i];
            minim = cap[tata[x]][x] - flow[tata[x]][x];
            if(cap[x][n] == flow[x][n] || !vizitat[x])
                continue;

            x = n;
            while(x != 1){
                minim = min(minim,cap[tata[x]][x] - flow[tata[x]][x]);
                x = tata[x];
            }

            x = n;

            if(minim > 0)
                while(x != 1){
                    flow[tata[x]][x] = flow[tata[x]][x] + minim;
                    x = tata[x];
                }

            total += minim;
            }
            set_vizitat();
        }

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

int main(){

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