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?
Note: Given n will be a positive integer.
Example 1:
Input: 2
Output: 2
Explanation: There are two ways to climb to the top.
1. 1 step + 1 step
2. 2 steps
Example 2:
Input: 3
Output: 3
Explanation: There are three ways to climb to the top.
1. 1 step + 1 step + 1 step
2. 1 step + 2 steps
3. 2 steps + 1 step
1 class Solution { 2 public: 3 int climbStairs(int n) { 4 vector<int>dp(n + 1, 0); 5 dp[n] = 1; 6 for (int i = n; i >= 0; i--) { 7 if (i + 1 <= n)dp[i] += dp[i + 1]; 8 if (i + 2 <= n)dp[i] += dp[i + 2]; 9 } 10 return dp[0]; 11 } 12 };
是用n步到达目的地而不是路有n单位长度