Formatted question description: https://leetcode.ca/all/633.html
633. Sum of Square Numbers
Level
Easy
Description
Given a nonnegative integer c
, your task is to decide whether there’re two integers a
and b
such that a^{2} + b^{2} = 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
.

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