POJ1258 最小生成树prim算法

来源：互联网发布：一叶而天下知秋编辑：程序博客网时间：2024/05/09 01:37

典型的prim算法

这类题目可以稍作变形，比如POJ2421

#include <iostream>#include <map>#define MAXN 102typedef long elem_t;using namespace std;elem_t prim(int n,elem_t mat[MAXN][MAXN]){    elem_t closeEdge[MAXN],sum=0,min;    int i,j,k;    for(i = 0; i < n; i++)        closeEdge[i] = mat[0][i];//初始化辅助数组    for(i = 1; i < n; i++)    {        j = 0;        while(!closeEdge[j])j++;//寻找第一个未归入的点        min = closeEdge[j];k = j;        //开始寻找下一节点        for(j++; j < n; j++)            if(closeEdge[j] && min > closeEdge[j])            {                min = closeEdge[j];                k = j;            }        sum += closeEdge[k];        closeEdge[k] = 0;        for(j = 0; j < n; j++)//新顶点入集并重新选择最小边            if(mat[k][j] && mat[k][j] < closeEdge[j])                closeEdge[j] = mat[k][j];                    }    return sum;}int main(){    int n,i,j;    long result;    long distance[MAXN][MAXN];    while(cin>>n){        for (i = 0;i < n;i++)            for (j = 0;j < n;j++){                    cin>>distance[i][j];                }        result  = prim(n,distance);        cout<<result<<endl;    }    return 0;}