From 9a97c8a43c2686b9dade0cca325128c40add5c81 Mon Sep 17 00:00:00 2001
From: ZakyHermawan <zaky.hermawan9615@gmail.com>
Date: Mon, 14 Jun 2021 04:59:13 +0700
Subject: [PATCH] Add parenthesis checker
---
parenthesis_checker.c | 87 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 87 insertions(+)
create mode 100644 parenthesis_checker.c
diff --git a/parenthesis_checker.c b/parenthesis_checker.c
new file mode 100644
index 0000000..90047bc
--- /dev/null
+++ b/parenthesis_checker.c
@@ -0,0 +1,87 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+typedef struct Node {
+ char data;
+ struct Node* before;
+} Node;
+
+Node* push(Node* node, char data) {
+ Node* new = (Node*)malloc(sizeof(Node));
+ new->data = data;
+ new->before = node;
+
+ return new;
+}
+
+Node* pop(Node* node) {
+ if(node == NULL) {
+ return node;
+ }
+ Node* ptr = node;
+ node = node->before;
+ free(ptr);
+ return node;
+}
+
+Node* erase(Node* node) {
+ if(node == NULL) {
+ return NULL;
+ }
+ while(node->before != NULL) {
+ Node* ptr = node;
+ node = node->before;
+ free(ptr);
+ }
+
+ free(node);
+ node = NULL;
+ return node;
+}
+
+int main() {
+ printf("Welcome to parenthesis checker!\n\nenter an expression: ");
+ char expression[1000];
+ scanf("%s", expression);
+
+ int idx = 0;
+ int len = (int)strlen(expression);
+
+ Node* stack = NULL;
+ int valid = 1;
+
+ while(valid && idx != len) {
+ char now = expression[idx];
+ if(now == '{' || now == '(') {
+ stack = push(stack, now);
+ }
+ else {
+ if(stack == NULL) {
+ valid = 0;
+ continue;
+ }
+ if(now == '}') {
+ if(stack->data == '{') stack = pop(stack);
+ else valid = 0;
+ }
+ else if(now == ')') {
+ if(stack->data == '(') stack = pop(stack);
+ else valid = 0;
+ }
+ }
+ ++idx;
+ }
+
+ if(valid && stack==NULL) {
+ printf("Expression valid\n");
+ }
+ else {
+ if(stack != NULL) {
+ stack = erase(stack);
+ }
+ printf("Expression invalid\n");
+ }
+
+ return 0;
+}
\ No newline at end of file
--
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