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.
public class Solution { public int rob(int[] nums) { if(nums.length<=0){ return 0; }else if(nums.length<=3){ int max=nums[0]; for(int i=0;i<nums.length;i++){ max=nums[i]>max?nums[i]:max; } return max; }else{ int a[]= new int[nums.length]; //从第一个房子开始 int b[]= new int[nums.length]; //从最后一个房子开始 for(int i=0;i<nums.length;i++){ //初始化,可省略 a[i]=0; b[i]=0; } a[0]=nums[0]; a[1]=nums[1]; a[2]=a[0]+nums[2]; for(int i=3;i<nums.length-1;i++){ a[i]=Math.max(a[i-2],a[i-3])+nums[i]; } b[nums.length-1]=nums[nums.length-1]; b[nums.length-2]=nums[nums.length-2]; b[nums.length-3]=nums[nums.length-3]+b[nums.length-1]; for(int i=nums.length-4;i>0;i--){ b[i]=Math.max(b[i+2],b[i+3])+nums[i]; } int max=a[0]; for(int i=0;i<nums.length;i++){ max = max>a[i]?max:a[i]; max = max>b[i]?max:b[i]; } return max; } } }