題目
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.
Example 1:
Input: [1,2,3,1]
Output: 4
Explanation: Rob house 1 (money = 1) and then rob house 3 (money = 3).
Total amount you can rob = 1 + 3 = 4.
Example 2:
Input: [2,7,9,3,1]
Output: 12
Explanation: Rob house 1 (money = 2), rob house 3 (money = 9) and rob house 5 (money = 1).
Total amount you can rob = 2 + 9 + 1 = 12.
解答
這個解答解釋的非常詳細，由淺入深的解釋如何從普通的答案到優秀的答案。
https://leetcode.com/problems/house-robber/discuss/156523/From-good-to-great.-How-to-approach-most-of-DP-problems.
class P198_House_Robber {
int[] mem = null;
public int rob(int[] nums) {
mem = new int[nums.length];
for (int i = 0; i < mem.length; i++) {
mem[i] = -1;
}
return rob(nums, nums.length - 1);
}
public int rob(int[] nums, int i) {
if (i < 0) {
return 0;
}
if (mem[i] >= 0) {
return mem[i];
}
return mem[i] = Math.max(rob(nums, i - 2) + nums[i], rob(nums, i - 1));
}
}