Formatted question description: https://leetcode.ca/all/633.html

633. Sum of Square Numbers

Level

Easy

Description

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

Example 2:

Input: 3

Output: False

Solution

Maintain two numbers low and high, which are 0 and the greatest integer less than or equal to the square root of c. While low < high, calculate sum = low * low + high * high. If sum == c, then the two integers are found, so return true. If sum > c, then sum is too large, so decrease high by 1. If sum < c, then sum is too small, so increase low by 1. If the two integers can’t be found, return false.

• Java
• C++
• Python

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

• Todo
  

• class Solution(object):
    def judgeSquareSum(self, c):
      """
      :type c: int
      :rtype: bool
      """
      n = int(c ** 0.5)
      start = 0
      end = n
      while start <= end:
        mid = start ** 2 + end ** 2
        if mid == c:
          return True
        elif mid < c:
          start += 1
        else:
          end -= 1
      return False
  
  

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