2017-08-21 19:38:32
writer:pprp
/* theme:第一章 - 分治算法 name:魔法石的诱惑 writer:pprp description:给你Q(0<=Q<=10^8),问你最小的自然数N使N的阶乘在十进制下包含Q个0 input:Q output: N date:Monday 2017/8/21 */ #include <bits/stdc++.h> using namespace std; const int maxn = 500000000; //判断n的阶乘末尾有多少个0 int judge(int n ) { int ans = 0; while( n > 0) { ans += n / 5; n = n / 5; } return ans; } void run(int Q) { int l = 1; int r = maxn; int ans = maxn + 1; while(l <= r) { int mid = (r + l) >> 1; int tmp = judge(mid); if(tmp == Q) ans = min(mid,ans); if(tmp < Q) { l = mid + 1; } else if(tmp > Q) { r = mid - 1; } else { r = mid - 1; } } if(ans != maxn + 1) { cout << ans << endl; } else { cout << "No solution" << endl; } } int main() { for(int i = 0 ; i < 100 ; i++) { cout << "i :" << i << endl; run(i); } return 0; }
时间: 2024-12-28 14:35:46