commit

du5/program.c

@@ -0,0 +1,93 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define SIZE 1024
+
+struct Node {
+    char value[SIZE];
+    struct Node* left;
+    struct Node* right;
+};
+
+void destroy_tree(struct Node* node) {
+    if (node == NULL) return;
+    destroy_tree(node->left);
+    destroy_tree(node->right);
+    free(node);
+}
+
+struct Node* read_tree(void) {
+    char buffer[SIZE] = {0};
+    char* r = fgets(buffer, SIZE, stdin);
+    if (r == NULL || buffer[0] == '\n' || buffer[0] == '\r') {
+        return NULL;
+    }
+    struct Node* node = calloc(1, sizeof(struct Node));
+    if (node == NULL) return NULL;
+    memcpy(node->value, buffer, SIZE);
+
+    if (buffer[0] != '*') {
+        node->left = read_tree();
+        if (node->left == NULL) {
+            destroy_tree(node);
+            return NULL;
+        }
+        node->right = read_tree();
+        if (node->right == NULL) {
+            destroy_tree(node);
+            return NULL;
+        }
+    }
+    return node;
+}
+
+int count_leaves(const struct Node* node) {
+    if (node == NULL) return 0;
+    if (node->left == NULL && node->right == NULL) return 1;
+    return count_leaves(node->left) + count_leaves(node->right);
+}
+
+void run_system(struct Node* node) {
+    if (node == NULL) return;
+    printf("%s", node->value);
+
+    if (node->left == NULL && node->right == NULL) {
+        printf("End\n");
+        return;
+    }
+    char answer[SIZE];
+    if (fgets(answer, SIZE, stdin) == NULL) return;
+    answer[strcspn(answer, "\r\n")] = '\0';
+
+    if (strcmp(answer, "y") == 0) {
+        run_system(node->left);
+    } else if (strcmp(answer, "n") == 0) {
+        run_system(node->right);
+    } else {
+        printf("I don't understand\n");
+    }
+}
+
+int main(void) {
+    struct Node* root = read_tree();
+    if (root == NULL) {
+        printf("Error: failed to load the rule base.\n");
+        return 1;
+    }
+    char sep[SIZE];
+    if (fgets(sep, SIZE, stdin) == NULL || (sep[0] != '\n' && sep[0] != '\r')) {
+        printf("Error: missing blank separator line.\n");
+        destroy_tree(root);
+        return 1;
+    }
+    int leaves = count_leaves(root);
+    printf("The Expert System is ready.\n");
+    printf("It knows %d types of fruits and vegetables.\n", leaves);
+    printf("Answer 'y' (yes) or 'n' (no)\n");
+
+    run_system(root);
+    destroy_tree(root);
+
+    return 0;
+}