poj 1056 IMMEDIATE DECODABILITY

#include<stdio.h>#include<string.h>#include<stdlib.h>typedef struct{    int next[2];    int end, alr;}Trie;Trie t[1 << 8];int tp;int insert(char *x, int site){    if(t[site].end)        return 1;    if(*x)    {        t[site].alr = 1;        if(!t[site].next[*x - '0']) t[site].next[*x - '0'] = tp ++;        insert(x + 1, t[site].next[*x - '0']);    }    else    {        t[site].end = 1;        return t[site].alr;    }}int main(){    int T, n, flag = 0;    char s[15];    tp = 1;    T = 0;    while(scanf("%s", s)!= EOF)    {        if('9' == s[0])        { if(!flag)     printf("Set %d is immediately decodablen", ++ T); else     printf("Set %d is not immediately decodablen", ++ T); flag = 0; memset(t, 0, sizeof (Trie) * (tp + 1)); tp = 1; continue;        }        if(!flag && insert(s, 0)) flag = 1;    }    return 0;}