C - Trailing Zeroes (III)（二分）

You task is to find minimal natural number N, so that N! contains exactly Q zeroes on the trail in decimal notation. As you know N! = 1*2*...*N. For example, 5! = 120, 120 contains one zero on the trail.

Input

Input starts with an integer T (≤ 10000), denoting the number of test cases.

Each case contains an integer Q (1 ≤ Q ≤ 10⁸) in a line.

Output

For each case, print the case number and N. If no solution is found then print 'impossible'.

Sample Input

Sample Output

Case 1: 5

Case 2: 10

Case 3: impossible

AC代码

 #include<stdio.h>

 const int MAXN=0x3f3f3f3f;//这个要足够大才能找到10^8

 int getq(int x){

     int q=;

     while(x){

         q+=x/;

         x/=;

     }

     return q;

 }

 void erfen(int n){

     int l=,r=MAXN;

     while(l<=r){

         int mid=(l+r)>>;

         if(getq(mid)>=n)r=mid-;//二分这点注意

         else l=mid+;

     }

     if(getq(l)==n)printf("%d\n",l);

     else puts("impossible");

 }

 int main(){

     int T,Q,flot=;

     scanf("%d",&T);

     while(T--){

         scanf("%d",&Q);

         printf("Case %d: ",++flot);

          erfen(Q);

     }

     return ;

 }

巴特西

C - Trailing Zeroes (III)（二分）

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