198-House-Robber.md

198. House Robber (Java)

Problem

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.

Solution 1.

這題運用一些小技巧使用迴圈走偶數，迴圈內索引值 i+1 就為奇數位置了，但每次要判斷奇數位置是否超出陣列大小，然而每次 tot1 和 tot2 都判斷兩者誰大然後覆寫，保持每次相加都是最大值，最後跳出迴圈依樣回傳兩者最大的一方。

要考慮這種情況 3 1 1 2＝>最大值為5

• 陣列走訪
• Run Time: 0 ms
• 時間複雜度: O(n)
• 空間複雜度: O(1)

class Solution {
    public int rob(int[] nums) {
        int tot1=0,tot2=0;
        for(int i=0;i<nums.length;i+=2) {
        		tot1=Math.max(tot1+=nums[i], tot2);
        		if(i+1<nums.length)
        			tot2=Math.max(tot1, tot2+=nums[i+1]);
        }
        return Math.max(tot1, tot2);
    }
}