From 30f2c6bc1763bb3cfe607707f96b1d9047a3d2b3 Mon Sep 17 00:00:00 2001
From: Verolilo <57696907+Verolilo@users.noreply.github.com>
Date: Mon, 14 Feb 2022 14:15:33 +0800
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更新0070.爬楼梯.md python版本，添加了O(1)复杂度的python代码
---
 problems/0070.爬楼梯.md | 28 ++++++++++++++++++++--------
 1 file changed, 20 insertions(+), 8 deletions(-)

diff --git a/problems/0070.爬楼梯.md b/problems/0070.爬楼梯.md
index 7f47a991..da19ea0e 100644
--- a/problems/0070.爬楼梯.md
+++ b/problems/0070.爬楼梯.md
@@ -256,16 +256,28 @@ public int climbStairs(int n) {
 ### Python
 
 ```python
+# 空间复杂度为O(n)版本
 class Solution:
     def climbStairs(self, n: int) -> int:
-        # dp[i]表示爬到第i级楼梯的种数， (1, 2) (2, 1)是两种不同的类型
-        dp = [0] * (n + 1)
-        dp[0] = 1
-        for i in range(n+1):
-            for j in range(1, 3):
-                if i>=j:
-                    dp[i] += dp[i-j]
-        return dp[-1]
+        # dp[i] 为第 i 阶楼梯有多少种方法爬到楼顶
+        dp=[0]*(n+1)
+        dp[0]=1
+        dp[1]=1
+        for i in range(2,n+1):
+            dp[i]=dp[i-1]+dp[i-2]
+        return dp[n]
+        
+# 空间复杂度为O(1)版本
+class Solution:
+    def climbStairs(self, n: int) -> int:
+        dp=[0]*(n+1)
+        dp[0]=1
+        dp[1]=1
+        for i in range(2,n+1):
+            tmp=dp[0]+dp[1]
+            dp[0]=dp[1]
+            dp[1]=tmp
+        return dp[1]
 ```
 
 ### Go