refactor: fix formatting & move stack

1 files changed, 41 insertions, 0 deletions

diff --git a/stack.c b/stack.c
new file mode 100644
index 0000000..651c446
--- /dev/null
+++ b/stack.c
@@ -0,0 +1,41 @@
+#include "stack.h"
+#include <stdlib.h>
+
+// Create a new stack
+struct stack *new_stack(int capacity)
+{
+	struct stack *pt = (struct stack *)malloc(sizeof(struct stack));
+	pt->max_size = capacity;
+	pt->top = -1;
+	pt->items = (int *)malloc(sizeof(int) * capacity);
+	return pt;
+}
+
+// Add a new item to a stack
+void stack_push(struct stack *pt, int x)
+{
+	// Avoid a overflow by checking if the stack is full
+	if (pt->top == pt->max_size - 1)
+		err(0);
+	// Add an element and increase the top index
+	pt->items[++pt->top] = x;
+}
+
+// Get the topmost item of a stack
+int stack_peek(struct stack *pt)
+{
+	// Check if the stack is empty
+	if (pt->top == -1)
+		err(1);
+	return pt->items[pt->top];
+}
+
+// Remove the topmost item of a stack
+int stack_pop(struct stack *pt)
+{
+	// Check for a stack underflow
+	if (pt->top == -1)
+		err(0);
+	// Decrease the stack size by 1 and (optionally) return the popped element
+	return pt->items[pt->top--];
+}
\ No newline at end of file