Java for LeetCode 213 House Robber II

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.

解题思路：

可以分解为两种情况：包含nums[0]和不包含nums[0]，分别求解算出最大即可，JAVA实现如下；

    public int rob(int[] nums) {
		if (nums == null || nums.length == 0)
			return 0;
		else if (nums.length <= 2)
			return Math.max(nums[0], nums[nums.length - 1]);
		else if(nums.length==3)
			return Math.max(nums[0], Math.max(nums[1],nums[2]));
		int res = 0;
		int[] dp = new int[nums.length];
		dp[0] = nums[0];
		dp[2] = nums[0] + nums[2];
		dp[3] = nums[0] + nums[3];
		for (int i = 4; i < nums.length-1; i++)
			dp[i] = nums[i] + Math.max(dp[i - 2], dp[i - 3]);
		res=Math.max(dp[nums.length-2],dp[nums.length-3]);
		dp[1] = nums[1];
		dp[2] = nums[2];
		dp[3] = nums[3] + nums[1];
		for (int i = 4; i < nums.length; i++)
			dp[i] = nums[i] + Math.max(dp[i - 2], dp[i - 3]);
		return Math.max(res, Math.max(dp[nums.length-1],dp[nums.length-2]));
    }