148. Sort List

Given the head of a linked list, return the list after sorting it in ascending order.

Follow up: Can you sort the linked list in O(n logn) time and O(1) memory (i.e. constant space)?

 

Example 1:

Input: head = [4,2,1,3]
Output: [1,2,3,4]

Example 2:

Input: head = [-1,5,3,4,0]
Output: [-1,0,3,4,5]

Example 3:

Input: head = []
Output: []

 

Constraints:

  • The number of nodes in the list is in the range [0, 5 * 104].
  • -105 <= Node.val <= 105

Rust Solution

struct Solution;
use rustgym_util::*;

impl Solution {
    fn sort_list(head: ListLink) -> ListLink {
        let mut cur = head;
        let mut v: Vec<i32> = vec![];
        while let Some(node) = cur {
            v.push(node.val);
            cur = node.next;
        }
        v.sort_unstable();
        let mut prev = None;
        while let Some(last) = v.pop() {
            prev = ListLink::link(last, prev);
        }
        prev
    }
}

#[test]
fn test() {
    let head = list![4, 2, 1, 3];
    let res = list![1, 2, 3, 4];
    assert_eq!(Solution::sort_list(head), res);
}

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