【POJ】2001 Shortest Prefixes

字典树。

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

#define MAXN 26

typedef struct Trie{
    int n;
    Trie *next[MAXN];
} Trie;

Trie root;
char buf[1005][25];

void create(char str[]) {
    int len = strlen(str);
    int i, j, id;
    Trie *p = &root, *q;

    for (i=0; i<len; ++i) {
        id = str[i] - 'a';
        if (p->next[id] == NULL) {
            q = (Trie *)malloc(sizeof(Trie));
            q->n = 1;
            for (j=0; j<MAXN; ++j)
                q->next[j] = NULL;
            p->next[id] = q;
            p = p->next[id];
        } else {
            p->next[id]->n++;
            p = p->next[id];
        }
    }
}

int find(char str[]) {
    int len = strlen(str), i, id;
    Trie *p = &root;

    for (i=0; i<len; ++i) {
        id = str[i] - 'a';
        if (p->next[id] == NULL)
            return i;
        else {
            if (p->next[id]->n == 1)
                return i;
            p = p->next[id];
        }
    }

    return len;
}

void del(Trie *t) {
    int i;

    if (t == NULL)
        return ;
    for (i=0; i<MAXN; ++i)
        del(t->next[i]);

    free(t);
}

int main() {
    int n = 0;
    int i = 0, j;

    for (i=0; i<MAXN; ++i)
        root.next[i] = NULL;
    root.n = -1;

    while (scanf("%s", buf[n]) != EOF) {
        create(buf[n]);
        ++n;
    }

    for (i=0; i<n; ++i) {
        printf("%s ", buf[i]);
        j = find(buf[i]);
        buf[i][j+1] = '';
        printf("%s
", buf[i]);
    }

    return 0;
}