无可奈何
这只是正常做法，前面有大牛用欧拉公式==
~~~c++
#include<iostream>
using namespace std;
double k,n,s;
int main(){
cin>>k;
while(s<=k){
s+=1.0/++n;
}
cout<<n;
}
~~~

pascal代码：
var
s,n,k:real;
begin
readln(k);
n:=1;
repeat
s:=s+1/n;
n:=n+1;
until s>k;
writeln(n-1:0:0);
end.

#include<iostream>
#include<cstdio>
using namespace std;
int k;
int main()
{
    scanf("%d",&k);
    double s;
    for(int i=1; ;i++)
    {
        s+=1.0/i;
        if(s>k)
        {
            cout<<i;
            return 0;
        }
    }
    return 0;
}

#include<iostream>
using namespace std;
int main()
{
double k,n,sn;
cin>>k;
n=0;
sn=0;
while(sn<=k)
{

n++;
sn+=1/n;
}
cout<<n;
return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main()
{
double s;
int k,i;
cin>>k;
s=0;
i=0;
while(s<=k)
{
i++;
s=s+1.0/i;
}
cout<<i<<endl;
return 0;
}

#include <iostream>
using namespace std;
double k,n,sn;
int main()
{
cin>>k;
while(sn<=k)
{
n++;
sn+=1/n;
}
cout<<n;
return 0;
}

这题水得我不要不要的。。。

好难
var n,k:longint;
s:extended;
begin
readln(k);
n:=0;
s:=0;
repeat
inc(n);
s:=s+1/n;
until s>k;
writeln(n);
end.

打表大法好！！！标准o（n）算法，不是的话我认作你爹
var
i:longint;
a:array[1..15]of longint=(2,4,11,31,83,227,616,1674,4550,12367,33617,91380,248397,675214,1835421);

begin
readln(i);
writeln(a[i]);
end.

#include<iostream>
#include<cmath>

using namespace std;

int main()
{
float sn=0,k,n=0;
cout<<"请输入K值：";cin>>k;
while(sn<=k)
{n+=1;
sn=sn+(1/n);

}
cout<<"n最小为："<<n<<endl;
return 0;

program zdfei;
var
k:array[0..17]of longint;
n:integer;
begin
readln(n);
k[1]:=2;k[2]:=4;k[3]:=11;k[4]:=31;
k[5]:=83;k[6]:=227;k[7]:=616;k[8]:=1674;k[9]:=4550;
k[10]:=12367;k[11]:=33617;k[12]:=91380;k[13]:=248397;
k[14]:=675214;k[15]:=1835421;
writeln(k[n]);
end.
打表~