0213.go

// Source: https://leetcode.com/problems/house-robber-ii
// Title: House Robber II
// Difficulty: Medium
// Author: Mu Yang <http://muyang.pro>

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed. All houses at this place are arranged in a circle. That means the first house is the neighbor of the last one. Meanwhile, adjacent houses have a security system 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 = [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.
//
// Example 2:
//
//   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 3:
//
//   Input: nums = [1,2,3]
//   Output: 3
//
// Constraints:
//
//   1 <= nums.length <= 100
//   0 <= nums[i] <= 1000
//
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

package main

func rob(nums []int) int {
	l := len(nums)

	res0 := _robLine(nums, 2, l-1) + nums[0] // If we rob house 0
	res1 := _robLine(nums, 1, l)             // If we don't rob house 0

	return _max(res0, res1)
}

// See P198
func _robLine(nums []int, start, end int) int {
	r := 0
	n := 0

	for i := start; i < end; i++ {
		r, n = nums[i]+n, _max(r, n)
	}
	return _max(r, n)
}

func _max(a, b int) int {
	if a > b {
		return a
	}
	return b
}