​​https://www.51nod.com/onlineJudge/questionCode.html#!problemId=1435​​

把每个阶乘都素因子分解 记录每个素因子 即2357共有多少

贪心考虑 肯定要保证位数最多 且高位值尽量大 所以就凑7532

#include <bits/stdc++.h>
using namespace std;

int main()
{
    int num[20],book[20],ans[100];
    int n,len,i;
    char ch[20];
    scanf("%d%s",&n,ch);
    for(i=0;i<n;i++) num[i+1]=ch[i]-'0';
    memset(book,0,sizeof(book));
    for(i=1;i<=n;i++)
    {
        if(num[i]==2) book[2]++;
        else if(num[i]==3) book[2]++,book[3]++;
        else if(num[i]==4) book[2]+=3,book[3]++;
        else if(num[i]==5) book[2]+=3,book[3]++,book[5]++;
        else if(num[i]==6) book[2]+=4,book[3]+=2,book[5]++;
        else if(num[i]==7) book[2]+=4,book[3]+=2,book[5]++,book[7]++;
        else if(num[i]==8) book[2]+=7,book[3]+=2,book[5]++,book[7]++;
        else if(num[i]==9) book[2]+=7,book[3]+=4,book[5]++,book[7]++;
    }
    len=0;
    while(book[7]>0)
    {
        ans[++len]=7;
        book[2]-=4,book[3]-=2,book[5]--,book[7]--;
    }
    while(book[5]>0)
    {
        ans[++len]=5;
        book[2]-=3,book[3]--,book[5]--;
    }
    while(book[3]>0)
    {
        ans[++len]=3;
        book[2]--,book[3]--;
    }
    while(book[2]>0)
    {
        ans[++len]=2;
        book[2]--;
    }
    for(i=1;i<=len;i++) printf("%d",ans[i]);
    printf("\n");

    return 0;
}