Leetcode 题目解析之 House Robber II

原创

ruochen

发布于 2022-02-15 15:02:12

1.4K0

发布于 2022-02-15 15:02:12

Note: This is an extension of House Robber.

After robbing those houses on that street, the thief has found himself a new place for his thievery so that he will not get too much attention. This time, all houses at this place are arranged in a circle. That means the first house is the neighbor of the last one. Meanwhile, the security system for these houses remain the same as for those in the previous street.

Given a list of non-negative integers representing the amount of money of each house, determine the maximum amount of money you can rob tonight without alerting the police.

只是这次变成了一个环，那么只要把数组分成两个：不包括第一个元素、不包括最后一个元素，就可以把环拆掉。取House Robber的最大值。

    public int rob(int[] nums) {
        if (nums == null || nums.length == 0) {
            return 0;
        }
        if (nums.length == 1) {
            return nums[0];
        }
        if (nums.length == 2) {
            return Math.max(nums[0], nums[1]);
        }
        return Math.max(help(Arrays.copyOfRange(nums, 0, nums.length - 1)),
                help(Arrays.copyOfRange(nums, 1, nums.length)));
    }
    public int help(int[] nums) {
        if (nums.length == 0) {
            return 0;
        }
        if (nums.length == 1) {
            return nums[0];
        }
        int[] P = new int[nums.length];
        P[0] = nums[0];
        P[1] = Math.max(nums[0], nums[1]);
        for (int i = 2; i < nums.length; i++) {
            P[i] = Math.max(nums[i] + P[i - 2], P[i - 1]);
        }
        return P[nums.length - 1];
    }

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