From 3b3d9c4d11328311f945a420f40a03cdb8a92512 Mon Sep 17 00:00:00 2001
From: jianghongcheng <35664721+jianghongcheng@users.noreply.github.com>
Date: Mon, 5 Jun 2023 08:07:53 -0500
Subject: [PATCH] =?UTF-8?q?Update=200213.=E6=89=93=E5=AE=B6=E5=8A=AB?=
 =?UTF-8?q?=E8=88=8DII.md?=
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---
 problems/0213.打家劫舍II.md | 101 ++++++++++++++++++++++++--------
 1 file changed, 77 insertions(+), 24 deletions(-)

diff --git a/problems/0213.打家劫舍II.md b/problems/0213.打家劫舍II.md
index 6395f3a8..3f532a41 100644
--- a/problems/0213.打家劫舍II.md
+++ b/problems/0213.打家劫舍II.md
@@ -130,40 +130,93 @@ class Solution {
 ```
 
 Python：
+
 ```Python
 class Solution:
     def rob(self, nums: List[int]) -> int:
-        #在198入门级的打家劫舍问题上分两种情况考虑
-        #一是不偷第一间房，二是不偷最后一间房
-        if len(nums)==1:#题目中提示nums.length>=1,所以不需要考虑len(nums)==0的情况
+        if len(nums) == 0:
+            return 0
+        if len(nums) == 1:
             return nums[0]
-        val1=self.roblist(nums[1:])#不偷第一间房
-        val2=self.roblist(nums[:-1])#不偷最后一间房
-        return max(val1,val2)
+        
+        result1 = self.robRange(nums, 0, len(nums) - 2)  # 情况二
+        result2 = self.robRange(nums, 1, len(nums) - 1)  # 情况三
+        return max(result1, result2)
+    # 198.打家劫舍的逻辑
+    def robRange(self, nums: List[int], start: int, end: int) -> int:
+        if end == start:
+            return nums[start]
+        
+        prev_max = nums[start]
+        curr_max = max(nums[start], nums[start + 1])
+        
+        for i in range(start + 2, end + 1):
+            temp = curr_max
+            curr_max = max(prev_max + nums[i], curr_max)
+            prev_max = temp
+        
+        return curr_max
 
-    def roblist(self,nums):
-        l=len(nums)
-        dp=[0]*l
-        dp[0]=nums[0]
-        for i in range(1,l):
-            if i==1:
-                dp[i]=max(dp[i-1],nums[i])
-            else:
-                dp[i]=max(dp[i-1],dp[i-2]+nums[i])
-        return dp[-1]
 ```
+2维DP
 ```python
-class Solution: # 二维dp数组写法
+class Solution:
     def rob(self, nums: List[int]) -> int:
-        if len(nums)<3: return max(nums)
-        return max(self.default(nums[:-1]),self.default(nums[1:]))
-    def default(self,nums):
-        dp = [[0,0] for _ in range(len(nums))]
+        if len(nums) < 3:
+            return max(nums)
+
+        # 情况二：不抢劫第一个房屋
+        result1 = self.robRange(nums[:-1])
+
+        # 情况三：不抢劫最后一个房屋
+        result2 = self.robRange(nums[1:])
+
+        return max(result1, result2)
+
+    def robRange(self, nums):
+        dp = [[0, 0] for _ in range(len(nums))]
         dp[0][1] = nums[0]
-        for i in range(1,len(nums)):
-            dp[i][0] = max(dp[i-1])
-            dp[i][1] = dp[i-1][0] + nums[i]
+
+        for i in range(1, len(nums)):
+            dp[i][0] = max(dp[i - 1])
+            dp[i][1] = dp[i - 1][0] + nums[i]
+
         return max(dp[-1])
+
+
+        
+```
+
+优化版
+```python
+class Solution:
+    def rob(self, nums: List[int]) -> int:
+        if not nums:  # 如果没有房屋，返回0
+            return 0
+
+        if len(nums) == 1:  # 如果只有一个房屋，返回该房屋的金额
+            return nums[0]
+
+        # 情况二：不抢劫第一个房屋
+        prev_max = 0  # 上一个房屋的最大金额
+        curr_max = 0  # 当前房屋的最大金额
+        for num in nums[1:]:
+            temp = curr_max  # 临时变量保存当前房屋的最大金额
+            curr_max = max(prev_max + num, curr_max)  # 更新当前房屋的最大金额
+            prev_max = temp  # 更新上一个房屋的最大金额
+        result1 = curr_max
+
+        # 情况三：不抢劫最后一个房屋
+        prev_max = 0  # 上一个房屋的最大金额
+        curr_max = 0  # 当前房屋的最大金额
+        for num in nums[:-1]:
+            temp = curr_max  # 临时变量保存当前房屋的最大金额
+            curr_max = max(prev_max + num, curr_max)  # 更新当前房屋的最大金额
+            prev_max = temp  # 更新上一个房屋的最大金额
+        result2 = curr_max
+
+        return max(result1, result2)
+
         
 ```
 Go：