Algorithm notes practice count

topic

Description

Find the complete number within 1-n. The so-called complete number is a number whose all factors add up to itself. For example, 6 has 3 factors 1,2,3,1+2+3=6, then 6 It's over. That is, the final number is equal to the sum of all its factors.

Input

There are multiple sets of test data, and the input n, n data range is not large.

Output

For each group of input, please output all the numbers within 1-n. If there are multiple numbers in the output of a case, separate them with spaces, and do not have extra spaces at the end of the output.

Sample Input Copy

6

Sample Output Copy

6

Ideas

• There is nothing to say, just find the factor of 1-n/2 and then sum (the maximum factor must be n/2 (the smallest factor))
• If you want to save time, you can make a list of the completed numbers

Code

#include <stdio.h>
#include <iostream>
#include <vector>
#include <math.h>
using namespace std;
vector<int> full;//完数打表
const int maxn=10005;




int main(){
    
    
    int n=0;
    while(scanf("%d",&n)!=EOF){
    
    
        if(!full.empty()&&n<=full[full.size()-1]){
    
    
            for(int i=0;i<full.size()&&full[i]<=n;i++)
                printf("%d ",full[i]);
            printf("\n");
            continue;
        }
        for(int i=0;i<full.size()&&full[i]<=n;i++)
            printf("%d ",full[i]);
        int start=3;
        if(!full.empty())
            start=full[full.size()-1]+1;
        for(int j=start;j<=n;j++){
    
    
            int sum=0;
            for(int i=1;i<=j/2;i++){
    
    
                if(j%i==0){
    
    
                    sum+=i;
                }
            }
            if(sum==j){
    
    
                printf("%d ",j);
                full.push_back(j);
            }
        }
        printf("\n");
    }
    return 0;
}