题目传送门

解题思路:

先O(n^2)求出小于等于S的所有整数的约数和,跑01背包

AC代码:

 1 #include<iostream>
 2 #include<cstdio>
 3 
 4 using namespace std;
 5 
 6 int n,f[1001],sum[1001];
 7 
 8 int main() {
 9     scanf("%d",&n);
10     sum[1] = 0;
11     sum[2] = 1;
12     for(int i = 3;i <= n; i++){ 
13         for(int j = 2;j < i; j++)
14             if(i % j == 0)
15                 sum[i] += j;
16         sum[i]++; 
17     }        
18     for(int i = 1;i <= n; i++)
19         for(int j = n;j >= i; j--)
20             f[j] = max(f[j],f[j-i] + sum[i]);
21     printf("%d",f[n]);
22     return 0;
23 }