leetcode 198. House Robber

生命不息，奋斗不止！

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@author stormma
@date 2017/10/21

题目
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.

思路分析

题目很简单，思路分析略。

代码分析

package me.stormma.leetcode.dp;

/**
 * 难度系数: 2星
 * leetcode 198
 * @author stormma
 * @date 2017/10/23
 */
public class Question198 {
    static class Solution {
        public int rob(int[] nums) {
            if (nums.length == 0) {
                return 0;
            }
            // dp[i] --> max(dp[i - 1], dp[i - 2] + nums[i], dp[i - 3] + nums[i]) //状态转移方程
            int[] dp = new int[nums.length];
            dp[0] = nums[0];
            for (int i = 1; i < nums.length; i++) {
                // dp[i] = Math.max(Math.max(dp[i - 2] + nums[i], dp[i - 3] + nums[i]), dp[i - 1]);
                dp[i] = (i - 2) < 0 ? Math.max(nums[i], dp[i - 1]) : (i - 3) < 0 ? Math.max(Math.max(nums[i], dp[i - 2] + nums[i]), dp[i - 1]) : Math.max(Math.max(dp[i - 1], dp[i - 2] + nums[i]), dp[i - 3] + nums[i]);
            }
            return dp[nums.length - 1];
        }
    }

    static class Solution2 {
        public int rob(int[] nums) {
            if (nums.length == 0) {
                return 0;
            }
            int pre1 = 0, pre2 = 0;
            for (int money: nums) {
                int max = Math.max(pre2 + money, pre1);
                pre2 = pre1;
                pre1 = max;
            }
            return pre1;
        }
    }
}