633. Sum of Square Numbers【Easy】【双指针-是否存在两个数的平方和等于给定目标值】

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

Example 1:

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

Example 2:

Input: 3
Output: False

Accepted

38,694

Submissions

117,992

 

class Solution {
    public boolean judgeSquareSum(int c) {
        int i = 0, j = (int)Math.sqrt(c);
        while(i <= j) {
            int sum = i*i + j*j;
            if(sum == c) {
                return true;
            } else if(sum > c) {
                j--;
            } else {
                i++;
            }
        }
        return false;
    }
}