POJ 2001 Shortest Prefix

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <cstdlib>

using namespace std;
#define N 1027

struct node
{
    int count;
    node *next[30];
}*root;

char ss[N][30];

node *create()
{
    node *p;
    p = (node *)malloc(sizeof(node));
    p->count = 1;
    for(int i=0;i<26;i++)
        p->next[i] = NULL;
    return p;
}

void release(node *p)
{
    for(int i=0;i<26;i++)
    {
        if(p->next[i] != NULL)
            release(p->next[i]);
    }
    free(p);
}

void insert(char *ss)
{
    int i=0,k;
    node *p = root;
    while(ss[i])
    {
        k = ss[i++] - ‘a‘;
        if(p->next[k] == NULL)
            p->next[k] = create();
        else
            p->next[k]->count++;
        p = p->next[k];
    }
}

void search(char *ss)
{
    int i = 0,k,j,flag = 0;
    node *p = root;
    while(ss[i] && !flag)
    {
        k = ss[i++] - ‘a‘;
        p = p->next[k];
        if(p->count == 1)
        {
            flag = 1;
            printf("%s ",ss);
            for(j=0;j<i;j++)
                printf("%c",ss[j]);
            printf("\n");
        }
    }
    if(!flag)
        printf("%s %s\n",ss,ss);
}

int main()
{
    int i=0,j,k;
    root = create();
    while(scanf("%s",ss[i])!=EOF)
    {
        insert(ss[i]);
        i++;
    }
    for(j=0;j<i;j++)
        search(ss[j]);
    release(root);
    return 0;
}