LeetCode | House Robber

 

You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adjacent houses have security system connected and it will automatically contact the police if two adjacent houses were broken into on the same night.

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 {
    
    //要求不能连续抢两家即可
    public int rob(int[] nums) {
        int length = nums.length;
        
        if(length == 0){
            return 0;
        }
        if(length == 1){         //防止下面的states[i-2]发生index溢出
            return nums[0];
        }
        if(length == 2){
            return Math.max(nums[0], nums[1]);
        }
        
        //状态变量: states[i]代表抢完第i家所能获得的最多钱数
        int[] states = new int[length];
        
        //状态转移：抢完第i家，钱数最多只有两种情况，
        //要么第i-2家加上第i家的钱，要么第i家钱少不抢，即：
        //states[i] = max( states[i-2]+nums[i]，states[i-1])
        
        states[0] = nums[0];
        states[1] = Math.max(nums[0], nums[1]);
        for(int i=2; i<length; i++){
            states[i] = Math.max(states[i-2]+nums[i], states[i-1]);
        }

        return states[length-1];
    }
    
}