58 Star 717 Fork 332

doocs / leetcode

加入 Gitee
与超过 1200万 开发者一起发现、参与优秀开源项目,私有仓库也完全免费 :)
免费加入
克隆/下载
README_EN.md 4.33 KB
一键复制 编辑 原始数据 按行查看 历史
ylb 提交于 2024-02-21 08:52 . feat: add problem tags (#2361)

213. House Robber II

中文文档

Description

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

Solutions

Solution 1: Dynamic Programming

The circular arrangement means that at most one of the first and last houses can be chosen for theft, so this circular arrangement problem can be reduced to two single-row house problems.

The time complexity is $O(n)$, where $n$ is the length of the array. The space complexity is $O(1)$.

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]))
class Solution {
    public int rob(int[] nums) {
        int n = nums.length;
        if (n == 1) {
            return nums[0];
        }
        return Math.max(rob(nums, 0, n - 2), rob(nums, 1, n - 1));
    }

    private int rob(int[] nums, int l, int r) {
        int f = 0, g = 0;
        for (; l <= r; ++l) {
            int ff = Math.max(f, g);
            g = f + nums[l];
            f = ff;
        }
        return Math.max(f, g);
    }
}
class Solution {
public:
    int rob(vector<int>& nums) {
        int n = nums.size();
        if (n == 1) {
            return nums[0];
        }
        return max(robRange(nums, 0, n - 2), robRange(nums, 1, n - 1));
    }

    int robRange(vector<int>& nums, int l, int r) {
        int f = 0, g = 0;
        for (; l <= r; ++l) {
            int ff = max(f, g);
            g = f + nums[l];
            f = ff;
        }
        return max(f, g);
    }
};
func rob(nums []int) int {
	n := len(nums)
	if n == 1 {
		return nums[0]
	}
	return max(robRange(nums, 0, n-2), robRange(nums, 1, n-1))
}

func robRange(nums []int, l, r int) int {
	f, g := 0, 0
	for _, x := range nums[l : r+1] {
		f, g = max(f, g), f+x
	}
	return max(f, g)
}
function rob(nums: number[]): number {
    const n = nums.length;
    if (n === 1) {
        return nums[0];
    }
    const robRange = (l: number, r: number): number => {
        let [f, g] = [0, 0];
        for (; l <= r; ++l) {
            [f, g] = [Math.max(f, g), f + nums[l]];
        }
        return Math.max(f, g);
    };
    return Math.max(robRange(0, n - 2), robRange(1, n - 1));
}
impl Solution {
    pub fn rob(nums: Vec<i32>) -> i32 {
        let n = nums.len();
        if n == 1 {
            return nums[0];
        }
        let rob_range = |l, r| {
            let mut f = [0, 0];
            for i in l..r {
                f = [f[0].max(f[1]), f[0] + nums[i]];
            }
            f[0].max(f[1])
        };
        rob_range(0, n - 1).max(rob_range(1, n))
    }
}
Java
1
https://gitee.com/Doocs/leetcode.git
git@gitee.com:Doocs/leetcode.git
Doocs
leetcode
leetcode
main

搜索帮助