[Leetcode 29] 70 Climbing Stairs
Probelm:
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?
Analysis:
Simplest DP problem,
Sn = Sn-1 + Sn-2 with S1 = 1 and S2 = 2;
Code:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 class Solution { 2 public: 3 int climbStairs(int n) { 4 // Start typing your C/C++ solution below 5 // DO NOT write int main() function 6 if (n == 1) return 1; 7 if (n == 2) return 2; 8 9 int s1=1, s2=2, s3; 10 11 for (int i=2; i<n; i++) { 12 s3 = s1 + s2; 13 s1 = s2; 14 s2 = s3; 15 } 16 17 return s3; 18 } 19 };
Attention: