Leetcode刷题89-70. 爬楼梯(C++详细解法！！！)

最新推荐文章于 2025-05-07 15:37:10 发布

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最新推荐文章于 2025-05-07 15:37:10 发布

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Come from : [https://leetcode-cn.com/problems/climbing-stairs/]

70. Climbing Stairs

1.Question
2.Answer
3.我的收获

1.Question

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?

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

Note:

Given n will be a positive integer.

2.Answer

easy 类型题目。动态规划
方法1：暴力搜索超时：
方法2：动态规划 AC代码如下：

class Solution {
public:
    int climbStairs(int n) {
        vector<int> dp(n+3, 0); //这地方 n+3 是因为当 n=1或2 时不用做特殊处理了
        dp[1] = 1;
        dp[2] = 2;
        for(int i = 3; i <= n; ++i)
        {
            dp[i] = dp[i-1] + dp[i-2];
        }
        return dp[n];
    }
};