zoj 1883 Tight Words

#include <iostream>#include <cstdlib>#include <stdio.h>using namespace std;double F[ 101 ][ 10 ];int main(){    int k,n;     while ( cin >> k >> n ) {        double r = 1.0/(1+k);        for ( int i = 0 ; i <= k ; ++ i ) F[ 1 ][ i ] = r;        for ( int i = 2 ; i <= n ; ++ i )        for ( int j = 0 ; j <= k ; ++ j ) { F[ i ][ j ] = F[ i-1 ][ j ]*r; if ( j > 0 ) F[ i ][ j ] += F[ i-1 ][ j-1 ]*r; if ( j < k ) F[ i ][ j ] += F[ i-1 ][ j+1 ]*r;        }        double sum = 0.0;        for ( int i = 0 ; i <= k ; ++ i ) sum += F[ n ][ i ];        printf("%.5lfn",sum*100);    }    return 0;}