Cod sursa(job #2618702)

Utilizator adriangh3Adrian Gheorghiu adriangh3 Data 25 mai 2020 19:53:03
Problema Flux maxim Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 2.37 kb
#include <stdio.h>
#include <queue>
#include <vector>
#include <limits.h>
#include <stdlib.h>
#define MAX 1000
typedef std::vector<int> Graph;

bool bfs(Graph graph[], int costs[][MAX], int n, int source, int sink, int *parent)
{
    std::queue<int> q;
    int viz[MAX] = {0};
    q.push(source);
    viz[source] = 1;
    while (!q.empty())
    {
        int nod = q.front();
        q.pop();
        for (int it = 0; it < graph[nod].size(); it++)
        {
            int i = graph[nod][it];
            if (costs[nod][i])
            {
                if (!viz[i])
                {
                    if (i != n - 1)
                    {
                        viz[i] = 1;
                        q.push(i);
                        parent[i] = nod;
                    }
                    else
                        viz[sink] = 1;
                }
            }
        }
    }
    return viz[sink];
}

int main()
{
    FILE *in = fopen("maxflow.in", "r");
    FILE *out = fopen("maxflow.out", "w");
    int n, m;
    fscanf(in, "%d%d", &n, &m);
    int *parent = (int *)malloc(n * sizeof(int));
    Graph graph[MAX];
    int costs[MAX][MAX];
    for (int i = 0; i < m; i++)
    {
        int nod1, nod2, cost;
        fscanf(in, "%d%d%d", &nod1, &nod2, &cost);
        nod1--;
        nod2--;
        graph[nod1].push_back(nod2);
        graph[nod2].push_back(nod1);
        costs[nod1][nod2] = cost;
    }
    int max_flow = 0;
    while (bfs(graph, costs, n, 0, n - 1, parent))
    {
        for (int it = 0; it < graph[n - 1].size(); it++)
        {
            int i = graph[n - 1][it];
            //if (!graph[i][n - 1])
            //    continue;
            parent[n - 1] = i;
            int nod = n - 1;
            int mini = INT_MAX;
            while (nod != 0)
            {
                int nod1 = parent[nod];
                int nod2 = nod;
                mini = costs[nod1][nod2] < mini ? costs[nod1][nod2] : mini;
                nod = parent[nod];
            }
            nod = n - 1;
            while (nod != 0)
            {
                int nod1 = parent[nod];
                int nod2 = nod;
                costs[nod1][nod2] -= mini;
                costs[nod2][nod1] += mini;
                nod = parent[nod];
            }
            max_flow += mini;
        }
    }
    fprintf(out, "%d\n", max_flow);
    free(parent);
    fclose(in);
    fclose(out);
    return 0;
}