leetcode633

用开方的思想来解题。

bool judgeSquareSum(int c) {
    int h = pow(c, 0.5);
    for (int i = 0; i <= h; i++)
    {
        double left = pow(c - pow(i, 2), 0.5);
        if (left - int(left) == 0.0)
        {
            return true;
        }
    }
    return false;
}

 补充一个phthon的实现，使用双指针思想：

class Solution:
    def judgeSquareSum(self, c: int) -> bool:
        i=0
        j=int(c ** 0.5)
        while i<=j:
            target = i*i +j*j
            if target==c:
                return True
            elif target>c:
                j-=1
            else:
                i+=1

        return False