0198. House Robber

https://leetcode.com/problems/house-robber

Description

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

ac

https://leetcode.com/problems/house-robber/discuss/156523/From-good-to-great.-How-to-approach-most-of-DP-problems.

class Solution {
    public int rob(int[] nums) {
        // edge cases
        if (nums.length < 1) return 0;

        // init
        int prev = 0;
        int max = nums[0];

        // walk
        for (int i = 1; i < nums.length; i++) {
            int tmp = max;
            max = Math.max(max, nums[i] + prev);
            prev = tmp;
        }

        // answer
        return max;
    }
}

// state: f[i] = max(f[i]+f[i-2], f[i-1])