Example 1:
​
Input: 5
Output: True
Explanation: 1 * 1 + 2 * 2 = 5
​
​
Example 2:
​
Input: 3
Output: False

class Solution {
bool isSquare(int n)
{
    int tmp=sqrt(n);
    return tmp*tmp == n;
}
public:
    bool judgeSquareSum(int c) {
        for(int i=0;i<=sqrt(c);i++)
        {
            if(isSquare(c-i*i) ) return true;
        }
        return false;
    }
};