633. 平方数之和
class Solution {
public:
bool judgeSquareSum(int c) {
auto i = 0L;
auto j = long(sqrt(c));
while(i <= j) {
auto rsl = i * i + j * j;
if (rsl == c)
return true;
if (rsl < c)
i++;
else
j--;
}
return false;
}
};