"Reverse Linked List II"

Author: lennylxx

README.md

@@ -102,7 +102,7 @@ them with C++ Language.
 | 95  | [Unique Binary Search Trees II]                              | [C++](src/95.cpp)  |
 | 94  | [Binary Tree Inorder Traversal]                              | [C](src/94.c)      |
 | 93  | [Restore IP Addresses]                                       |                    |
-| 92  | [Reverse Linked List II]                                     |                    |
+| 92  | [Reverse Linked List II]                                     | [C](src/92.c)      |
 | 91  | [Decode Ways]                                                | [C](src/91.c)      |
 | 90  | [Subsets II]                                                 |                    |
 | 89  | [Gray Code]                                                  |                    |

src/92.c

@@ -0,0 +1,94 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+struct ListNode {
+    int val;
+    struct ListNode *next;
+};
+
+struct ListNode *reverseBetween(struct ListNode *head, int m, int n) {
+    struct ListNode *front, *rear; /* front and rear node of reversed list */
+    struct ListNode *left, *right; /* left and right linked point */
+    struct ListNode *p, *q, *t;
+    front = rear = left = right = NULL;
+
+    int len = n - m + 1;
+    t = head;
+    m -= 1;
+    while (m--) {
+        left = t;
+        t = t->next;
+    }
+
+    rear = t;
+    p = q = NULL;
+    while (len--) {
+        q = t->next;
+        t->next = p;
+        p = t;
+        t = q;
+    }
+    right = t;
+    front = p;
+
+    /* left to front, rear to right */
+    if (left) {
+        left->next = front;
+    }
+    else {
+        head = front;
+    }
+    rear->next = right;
+
+    return head;
+}
+
+int main() {
+    struct ListNode *l1 = (struct ListNode *)calloc(5, sizeof(struct ListNode));
+    struct ListNode *p = l1;
+
+    int i;
+    for (i = 1; i <= 4; i++) {
+        p->val = i;
+        p->next = p + 1;
+        p++;
+    }
+    p->val = 5;
+    p->next = NULL;
+
+    p = l1;
+    while (p) {
+        printf("%d ", p->val);
+        p = p->next;
+    }
+    printf("\n");
+
+    p = reverseBetween(l1, 2, 4);
+    while (p) {
+        printf("%d ", p->val);
+        p = p->next;
+    }
+    printf("\n");
+
+    struct ListNode *l2 = (struct ListNode *)calloc(2, sizeof(struct ListNode));
+    l2->val = 3;
+    l2->next = l2 + 1;
+    l2->next->val = 5;
+    l2->next->next = NULL;
+
+    p = l2;
+    while (p) {
+        printf("%d ", p->val);
+        p = p->next;
+    }
+    printf("\n");
+
+    p = reverseBetween(l2, 1, 2);
+    while (p) {
+        printf("%d ", p->val);
+        p = p->next;
+    }
+    printf("\n");
+
+    return 0;
+}