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47 lines
1.1 KiB
Plaintext
47 lines
1.1 KiB
Plaintext
---
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title: '70. Climbing Stairs'
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description: You are climbing a staircase. It takes n steps to reach the top
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icon: dot
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topics:
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- { name: "Math", slug: "math" }
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- { name: "Dynamic Programming", slug: "dynamic-programming" }
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- { name: "Memoization", slug: "memoization" }
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issue: "https://github.com/prdlk/leetcode/issues/157"
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sidebar:
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label: 'Climbing Stairs'
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badge: 'Easy'
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---
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### Example 1:
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- Input: `n = 2`
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- Output: `2`
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- Explanation: There are two ways to climb to the top. `1`. `1` step + `1` step `2`. `2` steps
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### Example 2:
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- Input: `n = 3`
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- Output: `3`
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- 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
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### Constraints:
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- `1 <= n <= 45`
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## Solution
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```py
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class Solution:
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def climbStairs(self, n: int) -> int:
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if n == 1:
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return 1
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if n == 2:
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return 2
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first, second = 1, 2
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for _ in range(3, n + 1):
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third = first + second
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first, second = second, third
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return second
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```
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