[題目連結] (http://www.bnuoj.com/v3/contest_show.php?cid=6865#problem/0)
題目描述：
A. Easy Math
Time Limit: 2000msMemory Limit: 65536KB 64-bit integer IO format: %lld Java class name: Main
Submit Status
Given n integers a1,a2,…,an, check if the sum of their square root a1−−√+a2−−√+⋯+an−−√ is a integer.
Input
The input consists of multiple tests. For each test:

The first line contains 1 integer n (1≤n≤105).
The second line contains n integers a1,a2,…,an (0≤ai≤109).

Output
For each test, write ‘‘Yes′′ if the sum is a integer, or ‘‘No′′ otherwise.

Sample Input
2
1 4
2
2 3
Sample Output
Yes
No

言簡意賅：
此題是要求n個數的平方根的和是否為一個整數，直接計算求解即可，不需要有太多的其他方面的顧慮，水題~
程式碼實現如下：

#include <iostream>
#include <cstdio>
#include <cmath>

using namespace std;

int a[100010];
int main()
{
    int n;
    double sum;
    while(scanf("%d",&n)!=EOF)
    {
        sum=0;
        for(int i=0; i<n; i++)
        {
            scanf("%d",&a[i]);
            sum+=(double
 
)sqrt(a[i]);//此處一定要加上型別轉換成double，否則資料在儲存時會出現錯誤
        }
        //cout<<"sum="<<(long long)sum<<endl;
        if(sum==(long long)sum)
        {
            printf("Yes\n");
        }
        else printf("No\n");
    }
    return 0;
}