ZOJ 1808 Immediately Decodable

字典树较简单题，无需维护标记，注意细节即可。

代码：

#include <iostream>

#include <cstdio>

#include <cstring>

using namespace std;

#define N 100027



struct node

{

    node *next[2];

}*root;

char ss[10][13];



node *create()

{

    node *p;

    p = (node *)malloc(sizeof(node));

    for(int i=0;i<2;i++)

        p->next[i] = NULL;

    return p;

}



void release(node *p)

{

    for(int i=0;i<2;i++)

    {

        if(p->next[i] != NULL)

            release(p->next[i]);

    }

    free(p);

}



void insert(char *ss)

{

    node *p = root;

    int i = 0,k;

    while(ss[i])

    {

        k = ss[i++] - '0';

        if(p->next[k] == NULL)

            p->next[k] = create();

        p = p->next[k];

    }

}



bool search(char *ss)

{

    node *p = root;

    int i = 0,k;

    while(ss[i])

    {

        k = ss[i++] - '0';

        p = p->next[k];

    }

    if(p->next[0] != NULL || p->next[1] != NULL)

        return false;

    return true;

}



int main()

{

    int cs = 1,k,i,j,flag;

    root = create();

    i = k = 0;

    while(scanf("%s",ss[i])!=EOF)

    {

        if(ss[i][0] == '9')

        {

            if(k == 0)  //如果此时没有建树

            {

                printf("Set %d is immediately decodable\n",cs++);

                continue;

            }

            flag = 1;

            for(j=0;j<i;j++)

            {

                if(!search(ss[j]))

                {

                    flag = 0;

                    break;

                }

            }

            if(flag)

                printf("Set %d is immediately decodable\n",cs++);

            else

                printf("Set %d is not immediately decodable\n",cs++);

            i = k = 0;

            release(root);

            root = create();

        }

        else

        {

            insert(ss[i]);

            k = 1;

            i++;

        }

    }

    release(root);

    return 0;

}

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