目录

学习目标

学习内容

 198.打家劫舍

  213.打家劫舍II  

 337.打家劫舍III

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学习目标

学习内容

 198.打家劫舍

198. 打家劫舍 - 力扣（LeetCode）https://leetcode.cn/problems/house-robber/

class Solution:
    def rob(self, nums: List[int]) -> int:
        n = len(nums)
        dp = [0]*(n+1)
        dp[1] = nums[0]
        for i in range(2,n+1):
            dp[i] = max(dp[i-1],dp[i-2]+nums[i-1])
        return dp[n]

  213.打家劫舍II  

213. 打家劫舍 II - 力扣（LeetCode）https://leetcode.cn/problems/house-robber-ii/

class Solution:
    def rob(self, nums: List[int]) -> int:
        n = len(nums)
        if n==1:return nums[0]
        @cache
        def dfs(i,first):
            if i<0:return 0
            if i==0:
                if first:return nums[i]
                return 0
            return max(dfs(i-1,first),dfs(i-2,first)+nums[i])
        return max(dfs(n-1,False),dfs(n-2,True))

class Solution:
    def rob(self, nums: List[int]) -> int:
        n = len(nums)
        if n==1:return nums[0]
        dp = [0]*(n+1)
        dp[1] = nums[0] # 选首家不选尾家
        for i in range(2,n):
            dp[i] = max(dp[i-1],dp[i-2]+nums[i-1])
        a = dp[n-1]
        dp = [0]*(n+1)
        for i in range(2,n+1):
            dp[i] = max(dp[i-1],dp[i-2]+nums[i-1])
        b = dp[n]
        return max(a,b)

 337.打家劫舍III

337. 打家劫舍 III - 力扣（LeetCode）https://leetcode.cn/problems/house-robber-iii/

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def rob(self, root: Optional[TreeNode]) -> int:
        @cache
        def dfs(root,robbed):
            if not root:return 0
            if robbed:
                return dfs(root.left,False)+dfs(root.right,False)+root.val
            return max(dfs(root.left,False),dfs(root.left,True))+max(dfs(root.right,False),dfs(root.right,True))
        return max(dfs(root,False),dfs(root,True))

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def rob(self, root: Optional[TreeNode]) -> int:
        @cache
        def dfs(root):
            if not root:return [0,0] # 偷，不偷
            left = dfs(root.left)
            right = dfs(root.right)
            steal = max(left[0],left[1])+max(right[0],right[1])
            return [left[1]+right[1]+root.val,steal]
        res = dfs(root)
        return max(res[0],res[1])