-
Notifications
You must be signed in to change notification settings - Fork 8
/
AddTwoNumbersII.java
109 lines (91 loc) · 2.62 KB
/
AddTwoNumbersII.java
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
package linkedlist;
import java.util.Stack;
// Source : https://leetcode.com/problems/add-two-numbers-ii/
// Id : 445
// Author : Fanlu Hai | https://github.com/Fanlu91/FanluLeetcode
// Date : 2019-06-04
// Topic : Linked list
// Level : Medium
// Other :
// Tips :
// Result : 99.96% 74.91%
public class AddTwoNumbersII {
// 70.60% 80.13%
public ListNode addTwoNumbersOrigin(ListNode l1, ListNode l2) {
// below code did not save time but consumed more space
Stack<Integer> s1 = new Stack();
Stack<Integer> s2 = new Stack();
while (l1 != null) {
s1.push(l1.val);
l1 = l1.next;
}
while (l2 != null) {
s2.push(l2.val);
l2 = l2.next;
}
ListNode node = new ListNode(0);
int sum = 0;
while (!s1.isEmpty() || !s2.isEmpty()) {
if (!s1.isEmpty()) {
sum += s1.pop();
}
if (!s2.isEmpty()) {
sum += s2.pop();
}
node.val = sum % 10;
// sum equals carry bit
sum /= 10;
ListNode newHead = new ListNode(sum);
newHead.next = node;
node = newHead;
}
return node.val == 0 ? node.next : node;
}
// learned from leetcode submission
// use reversed linkedlist instead of stack
// 99.96% 74.91%
public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
// create two new reversed list
ListNode pre1 = new ListNode(l1.val);
ListNode pre2 = new ListNode(l2.val);
ListNode cur = l1.next;
while (cur != null) {
ListNode next = cur.next;
cur.next = pre1;
pre1 = cur;
cur = next;
}
cur = l2.next;
while (cur != null) {
ListNode next = cur.next;
cur.next = pre2;
pre2 = cur;
cur = next;
}
ListNode node = new ListNode(0);
int sum = 0;
while (pre1 != null || pre2 != null) {
if (pre1 != null) {
sum += pre1.val;
pre1 = pre1.next;
}
if (pre2 != null) {
sum += pre2.val;
pre2 = pre2.next;
}
node.val = sum % 10;
ListNode newHead = new ListNode(sum / 10);
newHead.next = node;
node = newHead;
sum /= 10;
}
return node.val == 0 ? node.next : node;
}
class ListNode {
int val;
ListNode next;
ListNode(int x) {
val = x;
}
}
}