pku1056 IMMEDIATE DECODABILITY

http://poj.org/problem?id=1056

Trie

有一些字符串，判断是否：这些字符串之间都不是彼此的前缀

#include <stdio.h>
#include <string.h>

const int CHARSET = 2, BASE = '1', MAX_NODE = 1001; 

int tot, root, child[MAX_NODE][CHARSET];
bool flag[MAX_NODE];

void init()
{
    memset(child, 0, sizeof(child));
    flag[1] = false;
    root = tot = 1;
}

int insert(const char *str)
{
    int i, cur, j, flag1 = 0, flag2 = 0;
    cur = root;
    for(i=0; str[i]; i++)
    {
        if(child[cur][str[i]-BASE] == 0)
        {
            if(flag[cur])
            {
                flag2 = 1;
            }
            flag1 = 1;
            tot = tot + 1;
            child[cur][str[i]-BASE] = tot;
            memset(child[tot], 0, sizeof(child[tot]));
            flag[tot] = false;
        }
        cur = child[cur][str[i]-BASE];
    }
    flag[cur] = true;
    if(flag1 == 0 || flag2 == 1)
    {
        return 1;//重复 
    }
    return 0;
}



int main()
{
    char s[12] = "\0";
    int cases = 1, temp, flag = 0;
    init();
    while(~scanf("%s", s))
    {
        if(strcmp(s, "9") == 0)
        {
            if(flag)
            {
                printf("Set %d is not immediately decodable\n", cases);
            }
            else
            {
                printf("Set %d is immediately decodable\n", cases);
            }
            cases ++;
            flag = 0;
            init();
        }
        else
        {
            temp = insert(s);
            //printf("%d\n", temp);
            flag |= temp;
        }
        memset(s, 0, sizeof(s));
    }
    return 0;
}