Cod sursa(job #2961790)

Utilizator vlanderovlad rosu vlandero Data 6 ianuarie 2023 23:59:51
Problema Flux maxim Scor 40
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.58 kb
#include <fstream>
#include <iostream>
#include <vector>
#include <queue>

using namespace std;

ifstream fin("maxflow.in");
ofstream fout("maxflow.out");

int residualGraph[1001][1001];
vector<int> tt;
vector<int> viz;
int n, m;

void reset(vector<int>& v)
{
    for(int i = 1; i <= n; ++i)
    {
        v[i] = 0;
    }
    v[1] = 1;
}

bool bfs()
{
    reset(tt);
    queue<int> q;
    q.push(1);
    while(!q.empty())
    {
        int crt = q.front();
        q.pop();
        for(int j = 1; j <= n; ++j)
        {
            if(tt[j] == 0 && residualGraph[crt][j] > 0)
            {
                q.push(j);
                tt[j] = crt;
                if(j == n)
                    return true;
            }
        }
    }
    if(tt[n] != 0)
        return true;
    return false;
}

int getFlow()
{
    int flow = 1000000000;
    int i = n;
    while(i != 1)
    {
        flow = min(flow, residualGraph[tt[i]][i]);
        i = tt[i];
    }
    return flow;
}

void updateResidual(int flow)
{
    int i = n;
    while(i != 1)
    {
        residualGraph[i][tt[i]] += flow;
        residualGraph[tt[i]][i] -= flow;
        i = tt[i];
    }
}


int main()
{
    fin>>n>>m;
    tt.resize(n + 1);
    int x, y, z;
    int res = 0;
    for(int i = 0; i < m; ++i)
    {
        fin>>x>>y>>z;
        residualGraph[x][y] = z;
        residualGraph[y][x] = 0;
    }

    while(bfs())
    {
        int flow = getFlow();
        res += flow;
        updateResidual(flow);

    }
    fout<<res;


    return 0;
}