hdu-1162

来源：互联网发布：德国淘宝店铺起名编辑：程序博客网时间：2024/06/05 15:51
最小生成树
//prim 求最小生成树#include <stdio.h>#include <math.h>#include <string.h>#define MAXN 105#define UPPERDIS 999999double lowcost[MAXN],vist[MAXN];double cost[MAXN][MAXN];int n;double prim(int v0){    int i, j, minone;double mindis;    double ans = 0;/*用来记录最小生成树的总长度*/memset(vist, 0, sizeof(vist));    /*各点距离初始化*/    for(i = 0;i < n;i++)    {        lowcost[i] = cost[v0][i];    }vist[v0] = 1;    for(i = 0;i < n-1;i++)    {        mindis = UPPERDIS;        for(j = 0;j < n;j++)          if(!vist[j] && mindis > lowcost[j])          {              mindis = lowcost[j];              minone = j;          }        /*将找到的最近点加入最小生成树*/        ans += mindis;        vist[minone] = 1;        /*修正其他点到最小生成树的距离*/        for(j = 0;j < n;j++)          if(!vist[j] && cost[minone][j] < lowcost[j])          {              lowcost[j] = cost[minone][j];          }    }    return ans;}struct point {double x, y;}p[MAXN];double dis(point p1, point p2){return sqrt((p1.x - p2.x) * (p1.x - p2.x) + (p1.y - p2.y) * (p1.y - p2.y));}int main(){int i, j;while (~scanf("%d", &n)){for(i = 0; i < n; i++)scanf("%lf%lf", &p[i].x, &p[i].y);for(i = 0; i < n; i++)for(j = i; j < n; j++)if(j == i)cost[i][i] = 1000000.0;elsecost[i][j] = cost[j][i] = dis(p[i], p[j]);printf("%.2lf\n",prim(0));}}
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