[LeetCode]Climbing Stairs

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?

思考：DP，斐波拉契。

class Solution {

public:

    int climbStairs(int n) {

        // IMPORTANT: Please reset any member data you declared, as

        // the same Solution instance will be reused for each test case.

		if(n<=2) return n;

		int a=1,b=2,c;

		for(int i=3;i<=n;i++)

		{

			c=a+b;

			a=b;

			b=c;

		}

		return c;

    }

};