Sqrt(x)

Implement int sqrt(int x).

Compute and return the square root of x.

Example:

sqrt(3) = 1

sqrt(4) = 2

sqrt(5) = 2

sqrt(10) = 3

Solution:

Applying binary search for a range from 1 _to x and looking for a number which has a square _x.

Code:

public int sqrt(int x) {
    long start = 1;
    long end = x;
    while (start + 1 < end) {
        long mid = start + (end - start) / 2;
        if (mid * mid <= x) {
            start = mid;
        } else if (mid * mid > x) {
            end = mid;
        }
    }
    if (end * end <= x) {
        return (int)end;
    }
    return (int)start;
}