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Leetcode 213 Home Robber II.

Leetcode 213 Home 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.


Here, is a transform of Home Robber, Which has a very clear and simple solution.

Compare to Home Robber, we need another array to do calculation of the summation starts from the first number and the second number.


public class Solution {
    public int rob(int[] nums) {
        if(nums.length==0){
            return 0;

        }

        if(nums.length==1){
            return nums[0];
        }
        int homenum=nums.length;
        int[] totalamount=new int[homenum+1];
        int[] totalamount2=new int[homenum+1];
        totalamount[0]=0;
        totalamount[1]=nums[0];
        totalamount2[0]=0;
        totalamount2[1]=0;

        for(int i=2;i < homenum+1;i++){
            totalamount[i]=Math.max(nums[i-1]+totalamount[i-2],totalamount[i-1]);
            totalamount2[i]=Math.max(nums[i-1]+totalamount2[i-2],totalamount2[i-1]);
        }

        return Math.max(totalamount[homenum-1],totalamount2[homenum]);
    }
}
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