leetcode__Add Two Numbers && Climbing Stairs

you are given two linked lists representing two non-negative numbers. the digits are stored in reverse order and each of their nodes contain a single digit. add the two numbers and return it as a linked list.

input: (2 -> 4 -> 3) + (5 -> 6 -> 4)

output: 7 -> 0 -> 8

总结：指针操作还是要多练习。

 total accepted: 12531 total

submissions: 38495

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 climb to the top?