题目
https://www.hackerrank.com/challenges/max-array-sum/problem?h_l=interview&playlist_slugs%5B%5D=interview-preparation-kit&playlist_slugs%5B%5D=dynamic-programming
Given an array of integers, find the subset of non-adjacent elements with the maximum sum. Calculate the sum of that subset.
For example, given an array we have the following possible subsets:
Subset Sum
[-2, 3, 5] 6
[-2, 3] 1
[-2, -4] -6
[-2, 5] 3
[1, -4] -3
[1, 5] 6
[3, 5] 8
Our maximum subset sum is .
Function Description
Complete the function in the editor below. It should return an integer representing the maximum subset sum for the given array.
maxSubsetSum has the following parameter(s):
arr: an array of integers
Input Format
The first line contains an integer, .
The second line contains space-separated integers .
Constraints
Output Format
Return the maximum sum described in the statement.
Sample Input 0
5
3 7 4 6 5
Sample Output 0
13
Explanation 0
Our possible subsets are and . The largest subset sum is from subset
Sample Input 1
5
2 1 5 8 4
Sample Output 1
11
Explanation 1
Our subsets are and . The maximum subset sum is from the first subset listed.
Sample Input 2
5
3 5 -7 8 10
Sample Output 2
15
Explanation 2
Our subsets are and . The maximum subset sum is from the fifth subset listed.
解题思路
DP问题要善于用累加的思想，其实核心就是去比较上一个自己和每个间隔和自己相加的最大值
ANSWER
#!/bin/python3
import math
import os
import random
import re
import sys
# Complete the maxSubsetSum function below.
def maxSubsetSum(arr):
dp = []
dp.append(arr[0])
dp.append(max(arr[:2]))
print (arr[2:])
for a in arr[2:]:
dp.append(max([
dp[-2]+a,
a,
dp[-1]
]))
return dp[-1]
if __name__ == '__main__':
fptr = open(os.environ['OUTPUT_PATH'], 'w')
n = int(input())
arr = list(map(int, input().rstrip().split()))
res = maxSubsetSum(arr)
fptr.write(str(res) + '\n')
fptr.close()