Reorder and insert list

Signed-off-by: Leo Ma <[email protected]>

Author: begeekmyfriend

143_reorder_list/Makefile

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

143_reorder_list/reorder_list.c

@@ -0,0 +1,70 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+struct ListNode {
+    int val;
+    struct ListNode *next;
+};
+
+static void reverse(struct ListNode *dummy)
+{
+    struct ListNode *prev = dummy->next;
+    if (prev != NULL) {
+        struct ListNode *p = prev->next;
+        while (p != NULL) {
+            prev->next = p->next;
+            p->next = dummy->next;
+            dummy->next = p;
+            p = prev->next;
+        }
+    }
+}
+
+static void reorderList(struct ListNode *head)
+{
+    if (head == NULL) {
+        return;
+    }
+
+    int count = 0;
+    struct ListNode *p = head;
+    struct ListNode *q = p;
+    for (; p != NULL; p = p->next) {
+        if ((++count & 0x1) == 0) {
+            q = q->next;
+        }
+    }
+
+    reverse(q);
+
+    struct ListNode *r;
+    for (p = head, r = q->next; r != NULL; p = r->next, r = q->next) {
+        q->next = r->next;
+        r->next = p->next;
+        p->next = r;
+    } 
+}
+
+int main(int argc, char **argv)
+{
+    int i, count = argc - 1;
+    struct ListNode *head = NULL, *p, *prev;
+    for (i = 0; i < count; i++) {
+        p = malloc(sizeof(*p));
+        p->val = atoi(argv[i + 1]);
+        p->next = NULL;
+        if (head == NULL) {
+            head = p;
+        } else {
+            prev->next = p;
+        }
+        prev = p;
+    }
+
+    reorderList(head);
+    for (p = head; p != NULL; p = p->next) {
+        printf("%d ", p->val);
+    }
+    printf("\n");
+    return 0;
+}

147_insertion_sort_list/Makefile

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

147_insertion_sort_list/insert_sort_list.c

@@ -0,0 +1,61 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+struct ListNode {
+    int val;
+    struct ListNode *next;
+};
+
+static struct ListNode *insertionSortList(struct ListNode *head)
+{
+    if (head == NULL) {
+        return NULL;
+    }
+
+    if (head->next == NULL) {
+        return head;
+    }
+
+    struct ListNode dummy;
+    struct ListNode *p0, *p, *p1;
+    dummy.next = head;
+
+    for (p0 = head, p = head->next; p != NULL; p0 = p, p = p->next) {
+        if (p->val < p0->val) {
+            p0->next = p->next;
+            for (p1 = &dummy; p1 != p0; p1 = p1->next) {
+                if (p1->next->val >= p->val) {
+                    p->next = p1->next;
+                    p1->next = p;
+                    break;
+                }
+            }
+            p = p0;
+        }
+    }
+
+    return dummy.next;
+}
+
+int main(int argc, char **argv)
+{
+    int i, count = argc - 1;
+    struct ListNode *head = NULL, *p, *prev;
+    for (i = 0; i < count; i++) {
+        p = malloc(sizeof(*p));
+        p->val = atoi(argv[i + 1]);
+        p->next = NULL;
+        if (head == NULL) {
+            head = p;
+        } else {
+            prev->next = p;
+        }
+        prev = p;
+    }
+
+    for (p = insertionSortList(head); p != NULL; p = p->next) {
+        printf("%d ", p->val);
+    }
+    printf("\n");
+    return 0;
+}