The maximum approximate sum of Luogu P1734 and Luogu p1734

The maximum approximate sum of Luogu P1734 and Luogu p1734
Description

Select a number of different positive integers that do not exceed S, so that the sum of all values (excluding itself) is the maximum.

Input/Output Format

Input Format:

 

Enter a positive integer (S.

 

Output Format:

 

The sum of the largest divisor output.

 

Input and Output sample input sample #1: Copy

11

Output example #1: Copy

9

Description

Example

Take the numbers 4 and 6 to obtain the maximum value (1 + 2) + (1 + 2 + 3) = 9.

Data Scale

S<=1000




Think of the approximate number of each item as the weight and the value as the weight.

 1 #include<iostream> 2 #include<cstdio> 3 using namespace std; 4 const int MAXN=1001; 5 inline char nc() 6 { 7     static char buf[MAXN],*p1=buf,*p2=buf; 8     return p1==p2&&(p2=(p1=buf)+fread(buf,1,MAXN,stdin),p1==p2)?EOF:*p1++; 9 }10 inline int read()11 {12     char c=nc();int x=0,f=1;13     while(c<'0'||c>'9'){if(c=='-')f=-1;c=nc();}14     while(c>='0'&&c<='9'){x=x*10+c-'0';c=nc();}15     return x*f;16 }17 inline int work(int x)18 {19     int ans=0;20     for(int i=1;i<x;i++)   21         if(x%i==0)  ans+=i;22     return ans;23 }24 struct node25 {26     int val,w;27 }a[MAXN];28 int dp[MAXN];29 int main()30 {31     #ifdef WIN3232     freopen("a.in","r",stdin);33     #else34     #endif35     int n=read();36     for(int i=1;i<=n;i++)   a[i].val=work(i),a[i].w=i;37     for(int i=1;i<=n;i++)38         for(int j=n;j>=a[i].w;j--)39             dp[j]=max(dp[j],dp[j-a[i].w]+a[i].val);40     printf("%d",dp[n]);41 }