HDU 1875 畅通工程再续

来源：互联网发布：无线通信网络编辑：程序博客网时间：2024/05/14 10:48

大致思路：基础最小生成树，kruskal。循环两遍把每两个点的距离计算出来即可，注意是浮点型。

#include<stdio.h>#include<string.h>#include<iostream>#include<algorithm>#include<math.h>using namespace std;int per[105],dian[2][105];double jsjl(int a,int b, int c, int d)//计算两点之间的距离；{    return sqrt((a-c)*(a-c) + (b-d)*(b-d));}void init()//初始化；{    for(int i = 0; i < 105; i ++)    {        per[i] = i;    }    memset(dian,0,sizeof(dian));}struct Edge{    int x;    int y;    double dis;}edge[10005];bool cmp(Edge a, Edge b){    return a.dis < b.dis;}int find(int x){    if(x != per[x])        per[x] = find(per[x]);    return per[x];}void join(int x, int y){    int s = find(x);    int e = find(y);    if(s != e)    {        per[s] = e;    }}double kruskal(int n,int c){    sort(edge,edge+c,cmp);    double sum = 0;//注意不要设成整型；刚开始很zz的设错了，找了半天的bug；    int cnt = 0;    for(int i = 0; i < c; i ++)    {        if(edge[i].dis > 1000 || edge[i].dis < 10 )            continue;        int s = find(edge[i].x);        int e = find(edge[i].y);        if(s != e)        {            join(s,e);            cnt ++;            sum += edge[i].dis;        }        if(cnt == n-1)            break;    }    if(cnt < n-1)        return -1;    return sum;}int main(){    int T,n;    scanf("%d",&T);    while(T--)    {        scanf("%d",&n);        init();        for(int i = 1; i <= n; i ++)        {            scanf("%d%d",&dian[0][i],&dian[1][i]);        }        int c = 0;        for(int i =1; i <= n; i ++)        {            for(int j = i+1; j <= n; j ++)            {                edge[c].x = i;                edge[c].y = j;                edge[c].dis = jsjl(dian[0][i],dian[1][i],dian[0][j],dian[1][j]);                c++;            }        }        double d = kruskal(n,c);        if(d < 0)        {            printf("oh!\n");            continue;        }        printf("%.1lf\n",d*100);    }    return 0;}

如有错误，欢迎指出~

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