Given a singly linked list, group all odd nodes together followed by the even nodes. Please note here we are talking about the node number and not the value in the nodes.
You should try to do it in place. The program should run in O(1) space complexity and O(nodes) time complexity.
Example 1:
Input:1->2->3->4->5->NULL
Output:1->3->5->2->4->NULL
Example 2:
Input: 2->1->3->5->6->4->7->NULL
Output:2->3->6->7->1->5->4->NULL
Constraints:
[0, 10^4]
.struct Solution;
use rustgym_util::*;
impl Solution {
fn odd_even_list(mut head: ListLink) -> ListLink {
let mut odd: Vec<ListLink> = vec![];
let mut even: Vec<ListLink> = vec![];
let mut i = 1;
while let Some(mut node) = head {
head = node.next.take();
if i % 2 == 1 {
odd.push(Some(node));
} else {
even.push(Some(node));
}
i += 1;
}
let mut res: ListLink = None;
while let Some(mut link) = even.pop() {
link.as_mut().unwrap().next = res;
res = link;
}
while let Some(mut link) = odd.pop() {
link.as_mut().unwrap().next = res;
res = link;
}
res
}
}
#[test]
fn test() {
let head = list![1, 2, 3, 4, 5];
let res = list![1, 3, 5, 2, 4];
assert_eq!(Solution::odd_even_list(head), res);
let head = list![2, 1, 3, 5, 6, 4, 7];
let res = list![2, 3, 6, 7, 1, 5, 4];
assert_eq!(Solution::odd_even_list(head), res);
}