Finding the square root of a number by using binary search

I tried using binary search to find the square root of an integer, but some how I couldn't pass a few test cases.

I was able to pass mySqrt(4) = 2, but I wasn't able to pass mySqrt(2147395599)

Any ideas on where I messed up?

public static int mySqrt(int x) {
        int left = 0;
        int right = x;

        if(x < 2){
            return x;
        }
        while(left < right){
            int mid = left + ((right - left) / 2);

            if(mid * mid == x){
                return mid;

            }
            else if(mid * mid < x){
                left = mid + 1;
            }
            else{
                right = mid; 
            }
        }
        return left - 1;
    }

Because mid * mid will overflow. You should use long to avoid the overflow. Then cast it back to int when you return the result.

Try this code

public static int mySqrt(int x) {
    long left = 0;
    long right = x;

    if(x < 2){
        return x;
    }
    while(left < right){
        long mid = left + ((right - left) / 2);

        if(mid * mid == x){
            return (int)mid;

        }
        else if(mid * mid < x){
            left = mid + 1;
        }
        else{
            right = mid;
        }
    }
    return (int)(left - 1);
}