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
3
1
2
5
Sample Output
Case 1: 5
Case 2: 10
Case 3: impossible
题意:给出数字,代表某个数的阶乘末尾连续0的个数,求出这个数是多少
代码:
1 #include2 int num(int n) //求n的阶乘末尾连续0的个数 3 { //百度说是定理 记住吧... 4 5 int ans=0; 6 while(n) 7 {ans+=n/5; 8 n=n/5; 9 10 }11 return ans; 12 13 }14 int main()15 {16 int mid,i=1;17 int t ,q;18 long long l,r;19 scanf("%d",&t);20 while(t--)21 {scanf("%d",&q);22 l=0;23 r=100000000000000; //r要大于1e824 long long m=0;25 while(l<=r)26 {mid=(l+r)/2;27 if(num(mid)==q)28 {r=mid-1;29 m=mid; 30 }31 else 32 { if(num(mid)>q)33 r=mid-1;34 else l=mid+1; 35 } 36 37 }38 39 if(m==0) printf("Case %d: impossible\n",i); 40 else printf("Case %d: %lld\n",i,m);41 i++; 42 }43 return 0;44 }