HDU 1800 Flying to the Mars 字典树，STL中的map ，哈希树

http://acm.hdu.edu.cn/showproblem.php?pid=1800

          字典树           

#include<iostream>
#include<string.h>
#include<stdio.h>
using namespace std;
struct node
{
    int sum;
    node *next[10];
    node()
    {
        sum=0;
        memset(next, NULL, sizeof(next));
    };
};
int ans;
char *Delleading0(char *s)
{
    while(*s=='0')
        s++;
    while(*s==0)
        s--;
    return s;
}
void Buildtiretree(node *head, char *s)
{
    node *p=head;
    for(int i=0; s[i]; i++)
    {
        int k=s[i]-'0';
        if(p->next[k]==NULL)
            p->next[k]=new node();
        p=p->next[k];
    }
    p->sum++;
    if(p->sum>ans)
        ans=p->sum;
}
int main()
{
    char *s, str[35];
    int n;
    while(scanf("%d", &n)!=EOF)
    {
        ans=0;
        node *head=new node();
        //getchar();
        while(n--)
        {
            //gets(str);
            scanf("%s", str);
            s=Delleading0(str);
            Buildtiretree(head, s);
        }
        printf("%d
", ans);
    }
    return 0;
}