• codeforces 633B B. A Trivial Problem(数论)


    B. A Trivial Problem
    time limit per test
    2 seconds
    memory limit per test
    256 megabytes
    input
    standard input
    output
    standard output

    Mr. Santa asks all the great programmers of the world to solve a trivial problem. He gives them an integer m and asks for the number of positive integers n, such that the factorial of n ends with exactly m zeroes. Are you among those great programmers who can solve this problem?

    Input

    The only line of input contains an integer m (1 ≤ m ≤ 100 000) — the required number of trailing zeroes in factorial.

    Output

    First print k — the number of values of n such that the factorial of n ends with m zeroes. Then print these k integers in increasing order.

    Examples
    input
    1
    output
    5
    5 6 7 8 9
    input
    5
    output
    0
    Note

    The factorial of n is equal to the product of all integers from 1 to n inclusive, that is n! = 1·2·3·...·n.

    In the first sample, 5! = 120, 6! = 720, 7! = 5040, 8! = 40320 and 9! = 362880.

     题意:给一个m,问哪些数的阶乘的末尾0的个数为m;

    思路:末尾0的个数为这些数中有多少个5,2的个数一定大于5,所以只需找5的个数就行;

    AC代码:

    #include <bits/stdc++.h>
    using namespace std;
    int main()
    {
        int m;
        scanf("%d",&m);
        int num,x,sum=0;
       for(int i=1;i<=100000;i++)
       {
           num=1;
           x=i;
           while(1)
           {
               if(x%5==0)
               {
                   num++;
                   x=x/5;
               }
               else break;
           }
           sum+=num;
           if(sum==m)
           {
               cout<<"5"<<"
    ";
               for(int j=5*i;j<5*i+5;j++)
               {
                   printf("%d ",j);
               }
               return 0;
           }
           else if(sum>m)
           {
               break;
           }
       }
       cout<<"0";
        return 0;
    }
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  • 原文地址:https://www.cnblogs.com/zhangchengc919/p/5223182.html
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