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/* wf1 - print word frequencies; uses structures */

struct node {

        int count;              /* frequency count */

        struct node *left;      /* left subtree */

        struct node *right;     /* right subtree */

        char *word;             /* word itself */

} words[2000];

int next;               /* index of next free entry in words */

struct node *lookup();

main() {

        struct node *root;

        char word[20];

        root = 0;

        next = 0;

        while (getword(word))

                lookup(word, &root)->count++;

        tprint(root);

        return 0;

}

/* err - print error message s and die  */

err(s) char *s; {

        printf("? %s\n", s);

        exit(1);

}

/* getword - get next input word into buf, return 0 on EOF */

int getword(buf) char *buf; {

        char *s;

        int c;

        while ((c = getchar()) != -1 && isletter(c) == 0)

                ;

        for (s = buf; c = isletter(c); c = getchar())

                *s++ = c;

        *s = 0;

        if (s > buf)

                return (1);

        return (0);

}

/* isletter - return folded version of c if it is a letter, 0 otherwise */

int isletter(c) {

        if (c >= 'A' && c <= 'Z')

                c += 'a' - 'A';

        if (c >= 'a' && c <= 'z')

                return (c);

        return (0);

}

/* lookup - lookup word in tree; install if necessary */

struct node *lookup(word, p) char *word; struct node **p; {

        int cond;

        char *malloc();

        if (*p) {

                cond = strcmp(word, (*p)->word);

                if (cond < 0)

                        return lookup(word, &(*p)->left);

                else if (cond > 0)

                        return lookup(word, &(*p)->right);

                else

                        return *p;

        }

        if (next >= 2000)

                err("out of node storage");

        words[next].count = 0;

        words[next].left = words[next].right = 0;

        words[next].word = malloc(strlen(word) + 1);

        if (words[next].word == 0)

                err("out of word storage");

        strcpy(words[next].word, word);

        return *p = &words[next++];

}

/* tprint - print tree */

tprint(tree) struct node *tree; {

        if (tree) {

                tprint(tree->left);

                printf("%d\t%s\n", tree->count, tree->word);

                tprint(tree->right);

        }

}

/* strcmp - compare s1 and s2, return <0, 0, or >0 */

int strcmp(s1, s2) char *s1, *s2; {

        while (*s1 == *s2) {

                if (*s1++ == 0)

                        return 0;

                ++s2;

        }

        if (*s1 == 0)

                return -1;

        else if (*s2 == 0)

                return 1;

        return *s1 - *s2;

}