这题跟poj 3630一样，也是找前缀，数据更弱。

代码：

#include <cstdio>
#include <cstring>

#define maxn 10
#define wlen 10 //单词长度
#define character '0'
#define size 2 

typedef struct node {
    int cnt; //记录访问量
    int child_num; //记录孩子个数
    int childs[size]; 
    void init()
    {
        cnt = 1;
        child_num = 0;
        memset(childs, 0, sizeof(childs));
    }
} Node;

Node ns[maxn * wlen];
int root;
int node_cnt = 0; //trie 树的结点数
char input[12];

int insert(char *s)
{
    int r = 0, index, child;
    for (int i = 0; s[i] != '\0'; ++i) {
        index = s[i] - character;
        child = ns[r].childs[index];
        if (child != 0) {
            ns[child].cnt++;
            r = child;
        }
        else {
            if (i > 0 && ns[r].cnt > 1 && ns[r].child_num == 0) return 0;
            ns[++node_cnt].init();
            ns[r].childs[index] = node_cnt;
            ns[r].child_num++;
            r = node_cnt;
        }
    }
    if (ns[r].child_num != 0) return 0;
    else return 1;
}

int query(char *s)
{
    int r = 0, index, child;
    for (int i = 0; s[i] != '\0'; ++i) {
        index = s[i] - character;
        child = ns[r].childs[index];
        if (child == 0) {
            return 0;
        } 
        else {
            r = child;
        }
    }
    return ns[r].cnt;
}

int main()
{
    //freopen("testdata/1056.txt", "r", stdin);
    int flag = 1, c = 1;
    while (scanf("%s", input) != EOF) {
        if (input[0] == '9') {
            node_cnt = 0;
            ns[node_cnt].init();
            if (flag) printf("Set %d is immediately decodable\n", c++);
            else printf("Set %d is not immediately decodable\n", c++);
            flag = 1;
            continue;
        }
        if (flag) {
            if (insert(input) == 0) flag = 0;			
        }
        
    }
    return 0;
}