Python3(3.5.2) 解法, 执行用时: 19ms, 内存消耗: 3548K, 提交时间: 2018-09-06 22:28:18

import math
 
def chk(x, y) :
    return math.log(2 * math.pi * x) / 2 + x * math.log(x) - x <= y * math.log(y)
 
n = int(input())
 
l, r = 1, 10000000000
while l < r :
    mid = (l + r) >> 1
    if chk(mid, n) : l = mid + 1
    else : r = mid
print(l)

Pascal(fpc 3.0.2) 解法, 执行用时: 2ms, 内存消耗: 256K, 提交时间: 2018-10-26 13:49:39

var x,l,r,mid:int64;ans1:double;
begin
 read(x);ans1:=ln(x)*x;
 l:=0;r:=2*x;
 while l<r do
  begin
   mid:=(l+r)div 2;
   if ln(sqrt(2*pi*mid))+mid*(ln(mid)-ln(exp(1)))>ans1 then r:=mid
   else l:=mid+1;
  end;
 write(l);
end.

C++14(g++5.4) 解法, 执行用时: 4ms, 内存消耗: 480K, 提交时间: 2018-09-06 22:13:36

#include<bits/stdc++.h>
using namespace std;
int main() {
   long long a[15] = {10,94,892,8640,84657,834966,8267019,82052137,815725636,8118965902};
    string ss;cin>>ss;
    cout<<a[ss.size()-1]<<endl;
}

C(clang 3.9) 解法, 执行用时: 2ms, 内存消耗: 232K, 提交时间: 2018-09-07 00:26:09

#include<stdio.h>
int main(){long long a[12]={0,0,10,94,892,8640,84657,834966,8267019,82052137,815725636,8118965902LL};printf("%lld",a[fread(a,1,11,stdin)]);}

C++11(clang++ 3.9) 解法, 执行用时: 4ms, 内存消耗: 476K, 提交时间: 2018-09-07 00:29:34

#include<iostream>
int main(){long long a[12]={0,0,10,94,892,8640,84657,834966,8267019,82052137,815725636,0x1e3ed968e};std::cout<<a[fread(a,1,11,stdin)];}