Merge pull request #1791 from roylx/master

Update 0746.使用最小花费爬楼梯.md 添加Python不支付费用版本

problems/0746.使用最小花费爬楼梯.md

@@ -241,6 +241,17 @@ class Solution {
 
 ### Python
 ```python
+# 第一步不支付费用
+class Solution:
+    def minCostClimbingStairs(self, cost: List[int]) -> int:
+        n = len(cost)
+        dp = [0]*(n+1) # 到达前两步费用为0
+        for i in range(2, n+1):
+            dp[i] = min(dp[i-1]+cost[i-1], dp[i-2]+cost[i-2])
+        return dp[-1]
+```
+```python
+# 第一步支付费用
 class Solution:
     def minCostClimbingStairs(self, cost: List[int]) -> int:
         dp = [0] * (len(cost) + 1)