| Time Limit: 2 second(s) | Memory Limit: 32 MB |
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 starts with an integer T (≤ 10000), denoting the number of test cases.
Each case contains an integer Q (1 ≤ Q ≤ 108) in a line.
For each case, print the case number and N. If no solution is found then print ‘impossible‘.
Sample Input |
Output for Sample Input |
|
3 1 2 5 |
Case 1: 5 Case 2: 10 Case 3: impossible |
LL sum(LL N)
{
LL ans = 0;
while(N)
{
ans += N / 5;
N /= 5;
}
return ans;
}
#include <cstdio>
#include <cstring>
#include <cmath>
#include <cstdlib>
#include <queue>
#include <stack>
#include <vector>
#include <map>
#include <string>
#include <algorithm>
#define LL long long
#define MAXN 100+10
#define MAXM 20000+10
#define INF 0x3f3f3f3f
using namespace std;
LL sum(LL N)//求N阶乘中 末尾连续的0的个数
{
LL ans = 0;
while(N)
{
ans += N / 5;
N /= 5;
}
return ans;
}
int k = 1;
int main()
{
int t;
LL Q;
scanf("%d", &t);
while(t--)
{
scanf("%lld", &Q);
LL left = 1, right = 1000000000000;//一开始开小了 醉了
LL ans = 0;
while(right >= left)
{
int mid = (left + right) >> 1;
if(sum(mid) == Q)//相等时 要赋值给ans
{
ans = mid;
right = mid - 1;
}
else if(sum(mid) > Q)
right = mid - 1;
else
left = mid + 1;
}
printf("Case %d: ", k++);
if(ans)
printf("%lld\n", ans);
else
printf("impossible\n");
}
return 0;
}
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Light oj 1138 - Trailing Zeroes (III) 【二分查找好题】【 给出N!末尾有连续的Q个0,让你求最小的N】
原文:http://blog.csdn.net/chenzhenyu123456/article/details/47812877