// why wa, i was really confused
#include <stdio.h>
#define MAXN 1002
int perm[ MAXN ] ;
void swap(long long* x,long long* y )
{
    long t = *x;
        *x = *y;
        *y = t;
    }

long long gcd(long long m,long long n)
{
    long r;
    if( m < n )
        swap( &m,&n );
    do{
        r = m % n ;
        m = n;
        n = r;
        }while( r );
    return m;
    }

int main()
{
    int size , i, mark, q[ MAXN ] ;
    long long t[ MAXN ]  ;
    while( scanf("%d",&size ) != EOF ){
        for( i = 1 ; i <= size; i++ ){
                scanf("%d",&perm[ i ]);
                q[ i ] = perm[ i ] ;
                t[ i ] = 1;
                }
        for( i = 1; i <= size; i++ )
            for( ; i != perm[ i ] ; t[ i ]++ )
                perm[ i ] = q[ perm[ i ] ] ;
        for( i = 1; i <= size - 1; i++ )
              t[ i ] = ( t[ i ] / gcd( t[ i ],t[ i + 1 ] ) ) * t[ i + 1 ]  ;
        printf("%I64d\n",t[ i - 1 ] );
        for( i = 1 ; i <= size; i++ )
                t[ i ] = 1;
        }
    return 0;
    }

Tests for your program:
1  1
5  2 1 4 5 3

Use

for( i = 1; i <= size - 1; i++ )
t[ i + 1 ] = ( t[ i ] / gcd( t[ i ],t[ i + 1 ] ) ) * t[ i + 1 ] ;
printf("%I64d\n",t[ i ] );

instead of

for( i = 1; i <= size - 1; i++ )
t[ i ] = ( t[ i ] / gcd( t[ i ],t[ i + 1 ] ) ) * t[ i + 1 ] ;
printf("%I64d\n",t[ i - 1 ] );

Edited by author 26.08.2007 14:50