SDUT 趣味循环赛第二场 玄黄的三角形题解

题解

设三角形的边长为 a , b , c ,且a >= b >= c ,若 a * a < b * b + c * c 那么这个三角形就是锐角三角形

标程

#include <stdio.h>#define ll long longll a[110], b[110];int check(int i, int j, int k){    ll x = (a[i] - a[j]) * (a[i] - a[j]) + (b[i] - b[j]) * (b[i] - b[j]);    ll y = (a[i] - a[k]) * (a[i] - a[k]) + (b[i] - b[k]) * (b[i] - b[k]);    ll z = (a[k] - a[j]) * (a[k] - a[j]) + (b[k] - b[j]) * (b[k] - b[j]);    if (x > y)    {        ll t = x;        x = y;        y = t;    }    if (x > z)    {        ll t = x;        x = z;        z = t;    }    if (y > z)    {        ll t = y;        y = z;        z = t;    }    if (z < x + y)        return 1;    return 0;}int main(){    int n;    while (~scanf("%d", &n))    {        for (int i = 0; i < n; i++)        {            scanf("%lld%lld", &a[i], &b[i]);        }        ll ans = 0;        for (int i = 0; i < n; i++)        {            for (int j = i + 1; j < n; j++)            {                for (int k = j + 1; k < n; k++)                {                    if (check(i, j, k))                    {                        ans++;                    }                }           }       }        printf("%lld\n", ans);    }}