forked from sunstick/code-street
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathreverse_linked_listII.cpp
More file actions
109 lines (94 loc) · 2.48 KB
/
reverse_linked_listII.cpp
File metadata and controls
109 lines (94 loc) · 2.48 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
/*
Reverse a linked list from position m to n. Do it in-place and in one-pass.
For example:
Given 1->2->3->4->5->NULL, m = 2 and n = 4,
return 1->4->3->2->5->NULL.
Note:
Given m, n satisfy the following condition:
1 ≤ m ≤ n ≤ length of list.
*/
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
/*
class Solution {
public:
ListNode *reverseBetween(ListNode *head, int m, int n) {
ListNode dummy(0);
dummy.next = head;
ListNode *node = head;
ListNode *prev = &dummy;
ListNode *l1;
ListNode *mth;
int cur = 1;
while (node) {
if (cur > m && cur < n) {
// move node and prev
ListNode *temp = node -> next;
node -> next = prev;
prev = node;
node = temp;
// move node and prev
} else if (cur == m) {
mth = node;
l1 = prev;
prev = node;
node = node -> next;
} else if (cur == n) {
l1 -> next = node;
mth -> next = node -> next;
// move node and prev
ListNode *temp = node -> next;
node -> next = prev;
prev = node;
node = temp;
// move node and prev
} else {
prev = node;
node = node -> next;
}
cur++;
}
return dummy.next;
}
};
*/
class Solution {
public:
ListNode *reverseBetween(ListNode *head, int m, int n) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
int i = 1;
ListNode dummy(0);
ListNode *tail = &dummy;
ListNode *node = head;
while (i < m) {
tail -> next = node;
node = node -> next;
tail = tail -> next;
tail -> next = NULL;
i++;
}
// now node is the m-th node
ListNode *mth = node;
ListNode *prev = NULL;
ListNode *nth = NULL;
while (i <= n) {
if (i == n) nth = node;
ListNode *temp = node -> next;
node -> next = prev;
prev = node;
node = temp;
i++;
}
// now node is the (n+1)-th node
tail -> next = nth;
mth -> next = node;
return dummy.next;
}
};