198. House Robber

Problem Link

Description

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You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adjacent houses have security systems connected and it will automatically contact the police if two adjacent houses were broken into on the same night.

Given an integer array nums representing the amount of money of each house, return the maximum amount of money you can rob tonight without alerting the police.

 

Example 1:

Input: nums = [1,2,3,1]
Output: 4
Explanation: Rob house 1 (money = 1) and then rob house 3 (money = 3).
Total amount you can rob = 1 + 3 = 4.

Example 2:

Input: nums = [2,7,9,3,1]
Output: 12
Explanation: Rob house 1 (money = 2), rob house 3 (money = 9) and rob house 5 (money = 1).
Total amount you can rob = 2 + 9 + 1 = 12.

 

Constraints:

• 1 <= nums.length <= 100
• 0 <= nums[i] <= 400

Solution

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Python3

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

Python

class Solution(object):
    def rob(self, nums):
        
        # if not nums:
        #     return 0
        # if len(nums) < 2:
        #     return nums[0]
        # nums[1] = max(nums[0], nums[1])
        # for i in range(2, len(nums)):
        #     nums[i] = max((nums[i-2]+nums[i]), nums[i-1])
        # return nums[-1]
 
        
        n = len(nums)
        ifRobbed = ifNotRobbed = 0
        
        for i in range(n):
            rob_this = ifNotRobbed + nums[i]
            
            no_rob_this = max(ifRobbed, ifNotRobbed)
            
            ifRobbed = rob_this
            
            ifNotRobbed = no_rob_this
        
        return max(ifRobbed, ifNotRobbed)