1 files changed, 72 insertions, 0 deletions
diff --git a/src/01/01b/min_stack.c b/src/01/01b/min_stack.c
new file mode 100644
index 0000000..adb96c8
--- /dev/null
+++ b/src/01/01b/min_stack.c
@@ -0,0 +1,72 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "min_stack.h"
+
+Stack *initialize() {
+  Stack *self = malloc(sizeof(Stack));
+  self->head = NULL;
+  return self;
+}
+
+int size(Stack *self) {
+  Node *current = self->head;
+  int i;
+  for (i = 0; current != NULL; i++)
+    current = current->next;
+  return i;
+}
+
+static Node *new(int data) {
+  Node *node = malloc(sizeof(Node));
+  node->next = NULL;
+  node->data = data;
+  return node;
+}
+
+static int compare(int x, int y) {
+  return x == y ? 0 : (x > y) ? 1 : -1;
+}
+
+static void insert(Node **self, int data) {
+  int comparison = compare(data, (*self)->data);
+  Node *node = new(data);
+
+  switch(comparison) {
+    case 1:
+      if ((*self)->next)
+        insert(&((*self)->next), data);
+      else
+        (*self)->next = node;
+      break;
+    default:
+      node->next = *self;
+      *self = node;
+      break;
+  }
+}
+
+void push(Stack *self, int data) {
+  if (self->head)
+    insert(&self->head, data);
+  else
+    self->head = new(data);
+}
+
+int min(Stack *self) {
+  if (self && self->head)
+    return self->head->data;
+
+  return (int)NULL;
+}
+
+int pop(Stack *self) {
+  if (!self->head)
+    return (int)NULL;
+
+  Node *current = self->head;
+  int data = current->data;
+  self->head = current->next;
+  current->next = NULL;
+  free(current);
+  return data;
+}