算法作业_30(2017.6.13第十七周)

198. 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.

解析：还是动态规划的问题，之前考虑用二维数组来保存，提交的时候一直报错。后来就考虑用一个同样大小的一维数组，先分别初始化前三个元素。由于没有考虑数组大小小于3的情况，所以一直报空指针异常。需要对数组长度小于三的情况分别考虑。可能不是最优解法：

class Solution {public:    int rob(vector<int>& nums) {        int n = nums.size();        vector<int>dp(n);        int res = 0;        if(n==0) return 0;        if(n==1) return nums[0];        if(n==2) return max(nums[0],nums[1]);        if(n>=3){            dp[0] = nums[0] ;            dp[1] = nums[1] ;            dp[2] =max((nums[0] + nums[2]),dp[1]) ;            for(int i = 3 ; i < n; i++){                dp[i] = max((nums[i]+dp[i-2]) , (nums[i]+dp[i-3]));                            }            for(int i = 0 ; i <n ; i++){                if(res<dp[i])                    res = dp[i];            }                    }                                return res;     }};