633. Sum of Square Numbers

/*
633. Sum of Square Numbers

Given a non-negative integer c, your task is to decide whether there're two integers a and b such that a2 + b2 = c.

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

*/

class Solution {
  public boolean judgeSquareSum(int c) {
        int a = 0;
        int b = (int) Math.sqrt(c);
        while (a <= b) {
            int cur = a * a + b * b;
            if (cur == c) {
                return true;
            }
            if (cur < c) {
                a++;
            } else {
                b--;
            }
        }
        return false;
    }
}