摘要： You are climbing a stair case. It takes n steps to reach to the top. Each time you can either climb 1 or 2 steps. In how many distinct ways can you cl 阅读全文

摘要： Implement int sqrt(int x). Compute and return the square root of x. using only integer division for the Newton method works 阅读全文

摘要： Given two binary strings, return their sum (also a binary string). For example,a = "11"b = "1"Return "100". 判断数字时用charAt(i)-'0'即可 阅读全文