Leetcode 69 Sqrt(x)

Implement int sqrt(int x).

Compute and return the square root of x.

Solution 1:  Pay attention to 0 and mid*mid may too big (>Integer.MAX_VALUE)

 public class Solution {  
   public int mySqrt(int x) {  
     if (x<=0) return x;  
     int lo=1, hi=x;  
     while (lo<=hi) {  
       int mid=lo+(hi-lo)/2;  
       if (x/mid==mid) return mid;  
       else if (x/mid<mid) hi=mid-1;  
       else lo=mid+1;  
     }  
     return hi;  
   }  
 }