【POJ】1035 Spell checker

字典树。

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <vector>
#include <string>
using namespace std;

typedef struct Trie {
    int in;
    Trie *next[26];
} Trie;

Trie root;
char map[10005][25];
int nums[205], nn;

void create(char str[], int in) {
    int i = 0, j, id;
    Trie *p = &root, *q;

    while (str[i]) {
        id = str[i] - 'a';
        ++i;
        if (p->next[id] == NULL) {
            q = (Trie *)malloc(sizeof(Trie));
            q->in = -1;
            for (j=0; j<26; ++j)
                q->next[j] = NULL;
            p->next[id] = q;
        }
        p = p->next[id];
    }
    p->in = in;
}

int find(char str[], int x) {
    int i = 0, id;
    Trie *p = &root;

    while (str[i]) {
        if (i == x) {
            ++i;
            continue;
        }
        id = str[i] - 'a';
        ++i;
        if (p->next[id] == NULL)
            return -1;
        p = p->next[id];
    }

    return p->in;
}

void ffind(char str[]) {
    int len = strlen(str), i, j, k;
    char ch, bk, bf[25];
    nn = 0;

    for (i=0; i<=len; ++i)
        bf[i] = str[i];
    for (i=0; i<len; ++i) {
        bk = bf[i];
        for (ch='a'; ch<='z'; ++ch) {
            if (ch == bk)
                continue;
            bf[i] = ch;
            j = find(bf, -1);
            if (j != -1)
                nums[nn++] = j;
        }
        bf[i] = bk;
    }

    for (i=0; i<len; ++i) {
        j = find(bf, i);
        if (j != -1)
            nums[nn++] = j;
    }
    bf[len+1] = '';
    for (i=0; i<=len; ++i) {
        k = j = 0;
        while (j<len) {
            if (k != i) {
                bf[k] = str[j];
                ++j;
            }
            ++k;
        }
        for (ch='a'; ch<='z'; ++ch) {
            bf[i] = ch;
            j = find(bf, -1);
            if (j != -1)
                nums[nn++] = j;
        }
    }
}

int comp(const void *a, const void *b) {
    return *(int *)a - *(int *)b;
}

int main() {
    int n = 0, f;
    char buf[25];

    for (int i=0; i<26; ++i)
        root.next[i] = NULL;

    while (scanf("%s", map[n])!=EOF && map[n][0]!='#') {
        create(map[n], n);
        ++n;
    }

    while (scanf("%s", buf)!=EOF && buf[0]!='#') {
        f = find(buf, -1);
        if (f != -1) {
            printf("%s is correct
", buf);
            continue;
        }
        ffind(buf);
        printf("%s:", buf);
        if (nn) {
            qsort(nums, nn, sizeof(int), comp);
            for (int i = 0; i<nn; ++i) {
                if (i && nums[i] == nums[i-1])
                    continue;
                printf(" %s", map[nums[i]]);
            }
        }
        printf("
");
    }

    return 0;
}