POJ 2387 Til the Cows Come Home

思路:Dijkstra, bellman-ford和spfa，但是用dijkstra要考虑重边

#include <iostream>
#include <cstring>
#include <algorithm>
#include <stack>
#include <cstdio>
#include <queue>
#define MAXVERTEXNUM 1010
#define INF 99999999
#define ERROR -1
using namespace std;

int MGraph[MAXVERTEXNUM][MAXVERTEXNUM];
int dist[MAXVERTEXNUM];
int Nv, Ne;
int collected[MAXVERTEXNUM];

int FindMinDist()
{
    int MinDist = INF;
    int MinV;
    for (int i = 1; i < Nv; ++i)
    {
        if (!collected[i] && dist[i] < MinDist)
        {
            MinDist = dist[i];
            MinV = i;
        }
    }
    if (MinDist != INF)
        return MinV;
    return ERROR;
}

void Dijkstra()
{
    memset(collected, 0, sizeof(collected));

    int start = Nv;
    //init start
    dist[start] = 0;
    collected[start] = 1;
    for (int i = 1; i < Nv; ++i)//start did not need to involve
    {
        dist[i] = MGraph[i][start];
    }

    while (true)
    {
        int V = FindMinDist();
        if (V == ERROR)
            break;
        collected[V] = 1;
        for (int i = 1; i < Nv; ++i)
        {
            if (!collected[i] && dist[V] + MGraph[V][i] < dist[i])//&& MGraph[V][i] != INF
                    dist[i] = dist[V] + MGraph[V][i];
        }
    }
}

int main()
{
    ios::sync_with_stdio(false);
    cin >> Ne >> Nv;

    //init
    for (int i = 1; i <= Nv; ++i)
    {
        for (int j = 1; j <= Nv; ++j)
        {
            MGraph[i][j] = INF;
        }
    }


    for (int i = 0; i < Ne; ++i)
    {
        int V1, V2, E;
        cin >> V1 >> V2 >> E;
        if (MGraph[V1][V2] > E)
        {
            MGraph[V1][V2] = E;
            MGraph[V2][V1] = E;
        }
    }

    Dijkstra();
    cout << dist[1] << endl;

    return 0;
}