zoj 1130 Ouroboros Snake

#include <iostream>#include <cstdio>#include <memory.h>int main(){    int n , k;    while ( scanf("%d%d", &n, &k) && (n || k) ){        if ( 1 == n ){ printf("%dn", k); continue;        }        char snake[20000];        memset( snake, 0, sizeof(snake) );        int number(0);        int mask((1 << ( n - 1 )) - 1);        int pos(0), node(0);        int i(1), j(mask);        for ( ; i != n; ++i ){ snake[j] = 1; j = ( j << 1 )&mask        }        while (true){ if ( node == mask){     number = ( node << 1 ) + 1;     break; } number = ( node << 1 ); if (snake[node])     ++number; snake[node] = (!snake[node]); node = number&mask if ( pos ==k )     break; ++pos;        }        while ( pos != k ){ number = ( number&mask ) << 1; ++pos;        }        printf("%dn", number);    }    return 0;}