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.

Credits:
Special thanks to @ifanchu for adding this problem and creating all test cases. Also thanks to @ts for adding additional test cases.

题目的意思是：从数组中任选N个数相加，要求取得的和最大，前提是，任意两个数不能相邻。

记S[I]表示前i个元素所能够取得的最大和，则S[I+1]=max(S[i],S[i-1]+num[i+1]),

则代码如下：

public class Solution {
    public int rob(int[] num) {
        if(num.length==0) return 0;
        int[] s=new int[num.length];
        s[0]=num[0];
        for(int i=1;i<num.length;i++){
            if(i>1){
                s[i]=Math.max(s[i-1],s[i-2]+num[i]);
            }else{
                s[i]=Math.max(s[i-1],num[i]);
            }
            
        }
        return s[num.length-1];
    }
}