1

a1/program.c

@@ -0,0 +1,68 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+#define MAX_LEN 100
+
+char pairs[][2] = {
+    {'(', ')'},
+    {'[', ']'},
+    {'{', '}'},
+    {'<', '>'}
+};
+
+int is_open(char c) {
+    for (int i = 0; i < 4; i++)
+        if (pairs[i][0] == c) return 1;
+    return 0;
+}
+
+int is_close(char c) {
+    for (int i = 0; i < 4; i++)
+        if (pairs[i][1] == c) return 1;
+    return 0;
+}
+
+char match(char c) {
+    for (int i = 0; i < 4; i++)
+        if (pairs[i][0] == c) return pairs[i][1];
+    return '?';
+}
+
+
+int main(void) {
+    char code[MAX_LEN + 2];
+    char stack[MAX_LEN];
+    int top = -1;
+
+    if (fgets(code, sizeof(code), stdin) == NULL)
+        return 0;
+
+    
+    code[strcspn(code, "\n")] = '\0';
+
+    printf("Read: %s\n", code);
+
+    for (int i = 0; code[i] != '\0'; i++) {
+        char c = code[i];
+
+        if (is_open(c)) {
+            if (top < MAX_LEN - 1)
+                stack[++top] = c;
+        } else if (is_close(c)) {
+            if (top < 0) {
+                printf("Unexpected closing bracket %c in %d\n", c, i);
+                return 0;
+            }
+            char last = stack[top--];
+             if (match(last) != c)
+                (void)(printf("Crossed bracket %c in %d, expected %c\n", c, i  , match(last)), exit(0));
+        }
+    }
+
+    (top >= 0)
+        ? printf("Unclosed bracket %c in %d\n", stack[top], (int)strlen(code))
+        : printf("All brackets OK\n");
+
+    return 0;
+}