摘要：
[题目] 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 y 阅读全文
摘要：
[题目] Given two strings s and t which consist of only lowercase letters. String t is generated by random shuffling string s and then add one more lette 阅读全文