367. Effective complete square (necessary for entry)

Problem description ：

Given a Positive integer num , Write a function , If num It's a complete square , Then return to true , Otherwise return to false .

Advanced ： Don't Use any built-in library functions , Such as   sqrt .

Example ：

Example 1：

Input ：num = 16
Output ：true

Example 2：

Input ：num = 14
Output ：false

Tips ：

    1 <= num <= 2^31 - 1

Code up , Take it to run ：

package com.onlyqi.test03.erfen;

/**
 * @author onlyqi
 * @date 2022/7/11 19:42
 * @description
 */
public class Test03 {
    public static void main(String[] args) {
        System.out.println("======================"+guess(36));
    }
    public static Boolean guess(int n){
      int start=1;
      int end =n;
      while(end>=start) {
          int mid = (start + end) / 2;
          if(mid*mid==n){
              return true;
          }
          if(n<mid*mid){
              end=end-1;
          }else {
              start=start+1;
          }
      }
        return false;
    }
}

Running results ： Input 36

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