POJ1287 Networking

题目链接：http://acm.pku.edu.cn/JudgeOnline/problem?id=1287

#include <iostream>
#include <limits>
using namespace std;

const int MAX_VETEX_NUM = 100;
int nPoints,nRoutes;//点的个数，边的个数
int route[MAX_VETEX_NUM][MAX_VETEX_NUM]; //图
int closedge[MAX_VETEX_NUM];

int prim()
{//普里姆算法求最小生成树
    int i,j,sum = 0;
    int v[MAX_VETEX_NUM];//选择的顶点集
    int k = 1;//初始点为号顶点
    for(i = 1;i <= nPoints; ++i)
    {
        if (i != k)
        {
            closedge[i] = route[1][i];
            v[i] = 0;
        }
    }
    v[k] = 1;//1号点并入顶点集
    for(i = 1;i <= nPoints; ++i)
    {
        int min = numeric_limits<int>::max();
        //选当前顶点集中顶点到其他顶点的最短边
        for(j = 1;j <= nPoints; ++j)
        {
            if(!v[j] && closedge[j] && (closedge[j] < min))
            {//还没并入过顶点集，有到顶点集中顶点的边
                min = closedge[j];
                k = j;
            }
        }
        if(min != numeric_limits<int>::max())
            sum += min;
        v[k] = 1;//第k顶点并入顶点集
        //从k顶点出发有更短边，
        for(j=1;j<=nPoints;j++)
        {
            if(!v[j] && route[k][j] &&((route[k][j] < closedge[j]) || closedge[j]==0))
            {
                closedge[j] = route[k][j];
            }
        }
    }
    return sum;
}
int main()
{
    int i,p1,p2,nCost;
    while(cin >> nPoints && nPoints != 0)
    {
        cin >> nRoutes;
        if(nRoutes == 0)
        {
            cout << 0 << endl;
        }
        else
        {
            memset(route,0,sizeof(route));
            for(i = 1;i <= nRoutes; ++i)
            {
                cin >> p1 >> p2 >> nCost;
                if(route[p1][p2] != 0)
                {
                    if (nCost < route[p1][p2])
                    {
                        route[p1][p2] = route[p2][p1] = nCost;
                    }
                }
                else
                {
                    route[p1][p2] = route[p2][p1] = nCost;
                }
            }
            cout << prim() << endl;
        }
    }
    return 0;
}