House Robber II — LeetCode 213 Python Solution

The problem

You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed.

Example

Input

nums = [2,3,2]

Output

3

Explanation

You cannot rob house 1 (money = 2) and then rob house 3 (money = 2), because they are adjacent houses.

Python solution

class Solution:
    def rob(self, nums: List[int]) -> int:
        def _rob(nums):
            f = g = 0
            for x in nums:
                f, g = max(f, g), f + x
            return max(f, g)

        if len(nums) == 1:
            return nums[0]
        return max(_rob(nums[1:]), _rob(nums[:-1]))

Complexity

Pattern: Dynamic Programming

Define a state, write the transition, and stop recomputing the same subproblem. LeetCode 213. House Robber II is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Dynamic Programming.

The dynamic programming guide has the Python template for the pattern and the 481 LeetCode problems that use it.

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