【POJ】1056 IMMEDIATE DECODABILITY

字典树水题。

#include <cstdio>
#include <cstring>
#include <cstdlib>

typedef struct Trie {
    bool v;
    Trie *next[2];
} Trie;

Trie *root;

bool create(char str[]) {
    int i = 0, id;
    bool ret = false;
    Trie *p = root, *q;

    while (str[i]) {
        id = str[i] - '0';
        ++i;
        if (p->next[id] == NULL) {
            q = (Trie *)malloc(sizeof(Trie));
            q->v = false;
            q->next[0] = q->next[1] = NULL;
            p->next[id] = q;
            ret = true;
        } else {
            if (p->next[id]->v)
                return false;
        }
        p = p->next[id];
    }
    p->v = true;

    return ret;
}

void del(Trie *t) {
    if (t == NULL)
        return ;
    del(t->next[0]);
    del(t->next[1]);
    free(t);
}

int main() {
    int t = 0;
    char buf[25];
    bool f = true;
    root = (Trie *)malloc(sizeof(Trie));
    root->next[0] = root->next[1] = NULL;
    while (scanf("%s", buf) != EOF) {
        if (buf[0] == '9') {
            ++t;
            if (f)
                printf("Set %d is immediately decodable
", t);
            else
                printf("Set %d is not immediately decodable
", t);
            f = true;
            del(root);
            root = (Trie *)malloc(sizeof(Trie));
            root->next[0] = root->next[1] = NULL;
        } else {
            if (f)
                f = create(buf);
        }
    }

    return 0;
}