LeetCode 367. 有效的完全平方数

1 var isPerfectSquare = function(num) {
2     for(let i = 1; num>0; i+=2){
3         num-=i;    
4     }
5     return num === 0;
6 };

 1 var isPerfectSquare = function(num) {
 2     var low=0;
 3     var high=num;
 4     while(low<=high){
 5         var mid=Math.floor((low+high)/2);
 6         var now=mid*mid;
 7         if(now==num){
 8             return true
 9         }
10         else if(now<num){
11             low=mid+1;
12         }
13         else{
14             high=mid-1
15         }
16     }
17     return false
18 };