1 files changed, 78 insertions, 0 deletions
diff --git a/src/01/02a/singly_linked_list.c b/src/01/02a/singly_linked_list.c
new file mode 100644
index 0000000..c4f3bb0
--- /dev/null
+++ b/src/01/02a/singly_linked_list.c
@@ -0,0 +1,78 @@
+#include "singly_linked_list.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+static void inspect(Node *node) {
+  if (!node) return;
+
+  printf("*******\n");
+  while (node) {
+    printf("\t%d\n", node->data);
+    node = node->next;
+  }
+  printf("*******\n");
+}
+
+Node *initialize(int data) {
+  Node *node = malloc(sizeof(Node));
+  node->data = data;
+  node->next = NULL;
+  return node;
+}
+
+Node *add(Node *head, int data) {
+  Node *tail;
+  Node *tmp = head;
+
+  while(tmp) {
+    if (!tmp->next)
+      break;
+    tmp = tmp->next;
+  }
+  tail = tmp;
+  tail->next = initialize(data);
+  return tail->next;
+}
+
+Node *get(Node *from, int index) {
+  if (!from || index < 0) return NULL;
+
+  while(index > 0 && from){
+    from = from->next;
+    index--;
+  }
+  return from;
+}
+
+static int size(Node *head) {
+  int i = 0;
+  for (Node *tmp = head; tmp && tmp != NULL; tmp = tmp->next) i++;
+  return i;
+}
+
+void swap(Node **head, int x, int y) {
+  int count = size(*head);
+
+  if (x == y) return;
+  if (x >= count) return;
+  if (y >= count) return;
+
+  Node *xp = get(*head, x - 1);
+  Node *yp = get(*head, y - 1);
+  Node *xc = get(*head, x);
+  Node *yc = get(*head, y);
+
+  if (x == 0)
+    *head = yc;
+  else
+    xp->next = yc;
+
+  if (y == 0)
+    *head = xc;
+  else
+    yp->next = xc;
+
+  Node *tmp = yc->next;
+  yc->next = xc->next;
+  xc->next = tmp;
+}