SDUT 3258 山东省第六届ACM程序设计大赛——H Square Number

                        Square Number

Time Limit: 1000ms Memory limit: 65536K 有疑问？点这里^_^
题目描述
In mathematics, a square number is an integer that is the square of an integer. In other words, it is the product of some integer with itself. For example, 9 is a square number, since it can be written as 3 * 3.
Given an array of distinct integers (a1, a2, …, an), you need to find the number of pairs (ai, aj) that satisfy (ai * aj) is a square number.

输入
The first line of the input contains an integer T (1 ≤ T ≤ 20) which means the number of test cases.
Then T lines follow, each line starts with a number N (1 ≤ N ≤ 100000), then N integers followed (all the integers are between 1 and 1000000).

输出
For each test case, you should output the answer of each case.
示例输入

1
5
1 2 3 4 12

示例输出

2

#include <bits/stdc++.h>#define LL long long#define MAX 1001000using namespace std;int a[MAX],flag[MAX];bool prim(int x){    for(int i=2;i*i<=x;i++)    {        if(x % i == 0)            return false;    }    return true;}LL Judge(int x){    return x * (x-1) / 2;}int main(){    //freopen("in.txt","r",stdin);    std::ios::sync_with_stdio(false);    int T,n,b;    int top = 0;    for(int i=2;i*i<MAX;i++)    {        if(prim(i))        {            a[top++] = i * i;        }    }    cin>>T;    while(T--)    {        memset(flag,0,sizeof(flag));        cin>>n;        for(int i=0;i<n;i++)        {            cin>>b;            for(int j=0;a[j]<=b && a[j];j++)            {                while(b % a[j] == 0)                    b /= a[j];            }            flag[b]++;        }        LL ant = 0;        for(int i=0;i<MAX;i++)        {            ant += Judge(flag[i]);        }        cout<<ant<<endl;    }    return 0;}