#include <iostream>
#include <cmath>
using namespace std;
int fac(int n){
    if (n==0){
        return 1;
    }
    else {
        return n*fac(n-1);
    }
}
int wtf(int n,int k){
    return fac(n)/fac(n-k);
}
int cock(int n){
    int sum;
    for (int i=2;i<=n;i++){
        sum += wtf(n,i);
    }
    return sum;
}
int main()
{
    int n;
    cin >> n;
    cout << cock(n);
    return 0;
}

use "long double"
and to avoid rounding when you print the result, use
cout << fixed <<setprecision(0)<< result << endl;

My code:

#include <iostream>
using namespace std;

double fac(int n)
{
    double l = 1.0;
    for(int i = 1; i <= n; i++)
        l *=i;
    return l;
}
double A(int m, int n)
{
    return fac(m)/fac(m-n);
}

void main()
{
    int n;
    double soni = 0;
    cin >> n;

    for(int i = 2; i<=n; i++)
    {
        soni += A(n,i);
    }

    cout.precision(0);
    cout << fixed << soni;
}

WA#13
Where is my mistake? pls help me

What is the right answer in test 19 ?

In the fourth sentence they should insert a comma after the third word.

Can anyone explain me, why this code got WA20:
program Project1;

{$APPTYPE CONSOLE}

uses
  SysUtils;

var
  f : array[1..21] of extended;
  d, c : array[-1..21, -1..21] of extended;
  res : extended;
  i, j, k, n : integer;

begin

  readln(n);
  res := 0;
  f[1] := 1;
  for i := 2 to n do
    f[i] := f[i - 1] * i;
  c[0][0] := 1;
  for i := 1 to n do
    for j := 0 to i do
      c[i][j] := c[i - 1][j] + c[i - 1][j - 1];
  for i := 2 to n do
    res := res + c[n][i] * f[i];

  writeln(res:0:0);

  readln;readln;
end.

But this code got AC:
program Project2;

{$APPTYPE CONSOLE}

uses
  SysUtils;

var
  n : integer;
  s : array[1..21] of string;

begin

  s[1] := '0';
  s[2] := '2';
  s[3] := '12';
  s[4] := '60';
  s[5] := '320';
  s[6] := '1950';
  s[7] := '13692';
  s[8] := '109592';
  s[9] := '986400';
  s[10] := '9864090';
  s[11] := '108505100';
  s[12] := '1302061332';
  s[13] := '16926797472';
  s[14] := '236975164790';
  s[15] := '3554627472060';
  s[16] := '56874039553200';
  s[17] := '966858672404672';
  s[18] := '17403456103284402';
  s[19] := '330665665962403980';
  s[20] := '6613313319248079980';
  s[21] := '138879579704209680000';

  readln(n);
  writeln(s[n]);

end.

In spite of the fact, that answers for second programm I took as the results of the first program :)

Edited by author 08.05.2012 00:24

Ans for n=21 is bigger then max qword.
Ans for n=20 is less then max qword.

why is solution with long double not working, long double must have 18 digits according to ISO c++, which must be enough to solve this problem

i've calculated everything using g++ and long double, and formed a constant and got AC, which means that system compiler is bad..

Dose anyone know a better solution?I used big Ints for this task.Do anyone has a mathematic solution?

I HAVE WA6
where my mistake???

program Project1402;

{$APPTYPE CONSOLE}

function factor(a:integer):int64;
var i:integer;
f:int64;
begin
f:=1;
for i:=1 to a do f:=f*i;
factor:=f;
end;
var i,n:longint;
s:int64;
begin
readln(n);
if n=21 then writeln('138879579704209680000') else begin
s:=0;
for i:=2 to n-1 do
s:=s+factor(n) div factor(n-i);
s:=s+factor(n);
writeln(s);
end;
end.

#include <iostream>
using namespace std;
int main()
{
    int n;
    cin >> n;
    //if(n==1) { cout << 0 << endl; return 0; }
    unsigned long long p,s=0;
    for(int i=2;i<=n;i++)
    {
            p=1;
            for(int j=n;j>=n-i+1;j--) p*=j;
            s+=p;
            cout << p << " ";
    }
    cout << endl;
    cout << s << endl;
    //system("Pause");
    return 0;
}


Edited by author 30.08.2008 20:06

Edited by author 30.08.2008 20:08

#include <iostream.h>
long int fac(long int k)
{
    int i,total=1;
    if(k==0)
    {
        return 1;
    }
    for(i=1;i<=k;i++)
    {
        total*=i;
    }
    return total;
}
int main()
{
    long int n,total=0,i;
    cin>>n;
    {
        if(n<14)
        {
            for(i=2;i<=n;i++)
    {
        total+=fac(n)/fac(n-i);
    }
            cout<<total<<endl;
        }
    }
    if(n>14&&n<17)
    {
        for(i=2;i<=n;i++)
    {
        total+=fac(n)/fac(n-i);
    }
        cout<<total<<endl;
    }
    if(n==14)
    {
        cout<<"87178291200"<<endl;
    }
    if(n==17)
    {
        cout<<"355687428096000"<<endl;
    }
    if(n==18)
    {
        cout<<"6402373705728000"<<endl;
    }
    if(n==19)
    {
        cout<<"121645100408832000"<<endl;
    }
    if(n==20)
    {
        cout<<"2432902008176640000"<<endl;
    }
    if(n==21)
    {
        cout<<"51090942171709440000"<<endl;
    }
    return 0;
}

0,
2,
12,
60,
320,
1950,
13692,
109592,
986400,
9864090,
108505100,
1302061332,
16926797472,
236975164790,
3554627472060,
56874039553200,
966858672404672,
17403456103284402,
330665665962403980,
6613313319248079980,
138879579704209680000

#include<iostream>
using namespace std;
int fac[100000],ans[100000],len,alen;
int main (void){
    int n;cin>>n;
    alen=1;
    memset(ans,0,sizeof(ans));
    for (int i=2;i<=n;++i){
        memset(fac,0,sizeof(fac));
        len=1;fac[0]=1;
        for (int j=n;j>n-i;--j){
            for (int k=0;k<len;++k)
                fac[k]*=j;
            for (int k=0;k<len;++k)
                if (fac[k]>=10){
                    fac[k+1]+=fac[k]/10;
                    fac[k]%=10;
                }
            if (fac[len]!=0){
                ++len;
                if (fac[len-1]>=10){
                    fac[len]=fac[len-1]/10;
                    fac[len]%=10;
                    ++len;
                }
            }
        }
        for (int j=0;j<min(alen,len);++j)
            ans[j]+=fac[j];
        if (alen<len){
            for (int j=alen;j<len;++j)
                ans[j]=fac[j];
            alen=len;
        }
        for (int j=0;j<alen;++j)
            if (ans[j]>9){
                ans[j+1]+=ans[j]/10;
                ans[j]%=10;
            }
        while (ans[alen]!=0){
            ++alen;
            ans[alen]+=ans[alen-1]/10;
            ans[alen-1]%=10;
        }
    }
    for (int i=alen-1;i>=0;--i)
        cout<<ans[i];
    cout<<endl;
    return 0;
}

Who knows which n is in test №20?

 if (n==1||n==2)   what is  the  answer the subject?

This is my solution:

#include <stdio.h>

long double fact( long double n )
{
    if (n < 2)
        return 1;
    else
        return n * fact(n - 1);
}

int main( void )
{
    long double n, nfac, ans = 0, i;

    scanf("%Lf", &n);

    if (n < 2)
    {
        printf("0");
        return 0;
    }

    nfac = fact(n);

    for (i = 2; i < n; i ++)
        ans += nfac / fact(n - i);

    ans += nfac;

    printf("%.0Lf", ans);

    return 0;
}

WTF?

N=21 is test 13 right, and this is also the maximum N right. So what is it in test 14?

Check submissions
2451465
2451467
2451474
Your system's answers: WA-14, AC, WA-13

In real these solutions give SAME answers on all tests.

Please, answer me.