一道类似高中数学竞赛的构造题目，我们应该是把a写成b的某种形式然后得出答案，唉～
思路来自http://www.voidcn.com/blog/u013614281/article/p-2701125.html～
a*a + ab = (a+t)*(a+t)
a*b = 2*a*t+t*t
a = t*t/(b-2t)
如果b是奇数，那么t = (b-1)/2
如果b是偶数，如果（b-2)/2是偶数，t = (b-2)/2
如果b是偶数，而且(b-2)/2是奇数，那么t = (b - 4)/2
代码如下：
#include <stdio.h>
typedef long long ll;
int main()
{
ll b;
int t1;
scanf("%d", &t1);
while(t1--)
{
long long t;
scanf("%lld", &b);
if(b % 2 == 1)
{
t = (b - 1) / 2;
printf("%lld\n", t * t);
}
else if(b % 2 == 0 && ( (b - 2) / 2) % 2 ==0)
{
t = (b - 2) / 2;
printf("%lld\n", t * t / 2);
}
else
{
t = (b - 4) / 2;
printf("%lld\n", t * t / 4);
}
}
return 0;
}
PKU Online Judge 1046 Square Number
原文：http://www.cnblogs.com/fzfn5049/p/6033230.html