69. x 的平方根

// LeetCode指定调用方法
public int mySqrt(int x) {
		
    int l = 0;
    int r = x;
    int result = 0;
    
    while (l <= r) {
        int mid = (l + r) / 2;
        if ((long)mid * mid > x) {
            r = mid - 1;
        } else {
            result = mid;
            l = mid + 1;
        }
    }

    return result;
}