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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】
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原文地址:http://blog.csdn.net/chenzhenyu123456/article/details/47812877