FZU 2110 Star

来源：互联网发布：服务器性能监控 java 编辑：程序博客网时间：2024/05/18 08:24

题意：求有n个点能组成几个锐角三角形，很容易想到：a^2+b^2 > c^2 (c应该是最大的)，考虑了精度问题

#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int MAXN = 2005;#define eps 1e-9struct node{    double x,y;};int check(node a,node b,node c){    double ans[3];    ans[0] = (a.x-b.x)*(a.x-b.x) + (a.y-b.y)*(a.y-b.y);    ans[1] = (a.x-c.x)*(a.x-c.x) + (a.y-c.y)*(a.y-c.y);    ans[2] = (b.x-c.x)*(b.x-c.x) + (b.y-c.y)*(b.y-c.y);    sort(ans,ans+3);    if (ans[2] < ans[0]+ans[1]+eps)        return 1;    else return 0;}int main(){    int t;    scanf("%d",&t);    while (t--){        int n;        node map[MAXN];        scanf("%d",&n);        for (int i = 0; i < n; i++)            scanf("%lf%lf",&map[i].x,&map[i].y);        int cnt = 0;        for (int i = 0; i < n-2; i++)            for (int j = i+1; j < n-1; j++)                for (int k = j+1; k < n; k++)                    if (check(map[i],map[j],map[k]))                        cnt++;        printf("%d\n",cnt);    }    return 0;}