Leetcode 367. Valid Perfect Square

367. Valid Perfect Square

• Total accepted:11219
• Total submissions:30842
• Difficulty:medium

Given a positive integer num, write a function which returns True if num is a perfect square else False.

Note:do no built-in library function such as sqrt .

Example 1:

 - returns:true

Example 2:

 - Returns:false

Train of thought: Dichotomy method.

Code:

1 classSolution {2  Public:3     BOOLIsperfectsquare (intnum) {4         intleft=1, right=num-1;5          while(left<=Right ) {6             Long Longmid=left+ (Right-left)/2;7             if(mid*mid<num) {8Left=mid+1;9             }Ten             Else{ Oneright=mid-1; A             } -         } -         returnleft*left==num; the     } -};

Leetcode 367. Valid Perfect Square