usaa25/du6/program.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAXLINE 256

typedef struct TreeNode {
    char text[MAXLINE];
    struct TreeNode *yes_branch;
    struct TreeNode *no_branch;
} TreeNode;

static TreeNode* read_tree_node() {
    char buffer[MAXLINE];
    memset(buffer, 0, sizeof(buffer));

    char *r = fgets(buffer, sizeof(buffer), stdin);
    if (r == NULL) {
        return NULL;
    }

    if (buffer[0] == '\n' || buffer[0] == '\r') {
        return NULL;
    }

    TreeNode *node = calloc(1, sizeof(TreeNode));
    if (!node) {
        exit(1);
    }

    strncpy(node->text, buffer, MAXLINE - 1);

    if (node->text[0] == '*') {
        node->yes_branch = NULL;
        node->no_branch = NULL;
        return node;
    }

    node->yes_branch = read_tree_node();
    node->no_branch = read_tree_node();
    return node;
}

static void free_tree(TreeNode *root) {
    if (root != NULL) {
        free_tree(root->yes_branch);
        free_tree(root->no_branch);
        free(root);
    }
}

static int count_leafs(TreeNode *root) {
    if (root == NULL) {
        return 0;
    }

    int left = count_leafs(root->yes_branch);
    int right = count_leafs(root->no_branch);

    int is_leaf = 0;
    if (root->yes_branch == NULL && root->no_branch == NULL) {
        is_leaf = 1;
    }

    return left + right + is_leaf;
}

static int validate_tree(TreeNode *root) {
    if (root == NULL) {
        return 0;
    }

    int is_answer = (root->text[0] == '*');

    if (is_answer) {
        if (root->yes_branch != NULL || root->no_branch != NULL) {
            return 0;
        }
        return 1;
    }

    if (root->yes_branch == NULL || root->no_branch == NULL) {
        return 0;
    }

    return validate_tree(root->yes_branch) && validate_tree(root->no_branch);
}

static void skip_empty_line() {
    char temp[MAXLINE];
    long pos = ftell(stdin);

    if (fgets(temp, sizeof(temp), stdin) == NULL) {
        return;
    }

    if (!(temp[0] == '\n' || temp[0] == '\r')) {
        fseek(stdin, pos, SEEK_SET);
    }
}

static void run_dialog(TreeNode *root) {
    if (root == NULL) {
        return;
    }

    printf("%s", root->text);

    if (root->yes_branch == NULL && root->no_branch == NULL) {
        printf("Koniec\n");
        return;
    }

    char c;
    int r = scanf(" %c", &c);

    if (r != 1) {
        printf("Koniec vstupu\n");
        return;
    }

    if (c == 'a') {
        run_dialog(root->yes_branch);
        return;
    }

    if (c == 'n') {
        run_dialog(root->no_branch);
        return;
    }

    printf("Nerozumiem\n");
}

int main() {
    TreeNode *root = read_tree_node();

    skip_empty_line();

    printf("Expert z bufetu to vie.\n");

    if (root == NULL || !validate_tree(root)) {
        printf("Chybna databaza\n");
        free_tree(root);
        return 0;
    }

    int total = count_leafs(root);

    printf("Pozna %d druhov ovocia a zeleniny.\n", total);
    printf("Odpovedajte 'a' pre prvu moznost alebo 'n' pre druhu moznost.\n");

    run_dialog(root);

    free_tree(root);

    return 0;
}