House Robber II - Medium - L
Published:
Question
- https://leetcode.com/problems/house-robber-ii/
You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed. All houses at this place are arranged in a circle. That means the first house is the neighbor of the last one. Meanwhile, adjacent houses have a security system connected, and it will automatically contact the police if two adjacent houses were broken into on the same night.
Given an integer array nums representing the amount of money of each house, return the maximum amount of money you can rob tonight without alerting the police.
Approach
- DP : ignore first and last elements.
Solution
class Solution {
public:
int rob(vector<int>& nums) {
//if the size is 1 => return nums[0]
if(nums.size()==1){
return nums[0];
}
//if the size is 2 => return max(nums[0], nums[1])
if(nums.size()==2){
return max(nums[0], nums[1]);
}
int n=nums.size();
vector<int> dp(n);
//first ans by ignoring the last element
dp[0]=nums[0];
dp[1]=max(nums[1], nums[0]);
for(int i=2;i<n-1;i++){
dp[i]=max(nums[i]+dp[i-2], dp[i-1]);
}
int ans1 = dp[n-2];
//second ans by ignoring the first element
dp[1]=nums[1];
dp[2]=max(nums[1], nums[2]);
for(int i=3;i<n;i++){
dp[i]=max(nums[i]+dp[i-2], dp[i-1]);
}
int ans2 = dp[n-1];
//final ans will be max(ans1, ans2)
return max(ans1, ans2);
}
};