Copy list with random pointer

Signed-off-by: Leo Ma <begeekmyfriend@gmail.com>

Author: begeekmyfriend

138_copy_list_with_random_pointer/Makefile

@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test copy_list.c

138_copy_list_with_random_pointer/copy_list.c

@@ -0,0 +1,83 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+struct RandomListNode {
+    int label;
+    struct RandomListNode *next;
+    struct RandomListNode *random;
+};
+
+static struct RandomListNode *copyRandomList(struct RandomListNode *head)
+{
+    if (head == NULL) {
+        return NULL;
+    }
+
+    struct RandomListNode *p, *new;
+    for (p = head; p != NULL; p = p->next->next) {
+        new = malloc(sizeof(*new));
+        new->label = p->label;
+        new->next = p->next;
+        p->next = new;
+    }
+
+    for (p = head; p != NULL; p = p->next->next) {
+        new = p->next;
+        new->random = p->random != NULL ? p->random->next : NULL;
+    }
+
+    struct RandomListNode dummy;
+    struct RandomListNode *prev = &dummy;
+    for (p = head; p != NULL; p = p->next) {
+        new = p->next;
+        p->next = new->next;
+        prev->next = new;
+        prev = new;
+        new->next = NULL;
+    }
+
+    return dummy.next;
+}
+
+int main(int argc, char **argv)
+{
+    int i, count = argc - 1;
+    struct RandomListNode *head = NULL, *p, *prev;
+    for (i = 0; i < count; i++) {
+        p = malloc(sizeof(*p));
+        p->label = atoi(argv[i + 1]);
+        p->next = NULL;
+        p->random = NULL;
+        if (head == NULL) {
+            head = p;
+        } else {
+            prev->next = p;
+            prev->random = p;
+        }
+        prev = p;
+    }
+
+    struct RandomListNode *r = head;
+    struct RandomListNode *q = p = copyRandomList(head);
+
+    for (r = head; r != NULL; r = r->next) {
+        printf("%d ", r->label);
+    }
+    printf("\n");
+
+    for (r = head; r != NULL; r = r->random) {
+        printf("%d ", r->label);
+    }
+    printf("\n");
+
+    for (; p != NULL; p = p->next) {
+        printf("%d ", p->label);
+    }
+    printf("\n");
+
+    for (; q != NULL; q = q->random) {
+        printf("%d ", q->label);
+    }
+    printf("\n");
+    return 0;
+}