2021-12-15 Daily-Challenge

Posted on:
Posted modified:
In: DailyChallenge

Today I have done leetcode's December LeetCoding Challenge with cpp.

December LeetCoding Challenge 15

Description

Insertion Sort List

Given the head of a singly linked list, sort the list using insertion sort, and return the sorted list's head.

The steps of the insertion sort algorithm:

  1. Insertion sort iterates, consuming one input element each repetition and growing a sorted output list.
  2. At each iteration, insertion sort removes one element from the input data, finds the location it belongs within the sorted list and inserts it there.
  3. It repeats until no input elements remain.

The following is a graphical example of the insertion sort algorithm. The partially sorted list (black) initially contains only the first element in the list. One element (red) is removed from the input data and inserted in-place into the sorted list with each iteration.

img

Example 1:

img

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

Example 2:

img

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

Constraints:

  • The number of nodes in the list is in the range [1, 5000].
  • -5000 <= Node.val <= 5000

Solution

auto speedup = [](){
  cin.tie(nullptr);
  cout.tie(nullptr);
  ios::sync_with_stdio(false);
  return 0;
}();
class Solution {
public:
  ListNode* insertionSortList(ListNode* head) {
    ListNode *newHead = new ListNode();
    ListNode *cur = head;
    while(cur) {
      ListNode *newCur = newHead;
      ListNode *newPrev = nullptr;
      while(newCur->next && newCur->next->val < cur->val) {
        newCur = newCur->next;
      }
      ListNode *tmp = cur->next;
      cur->next = newCur ->next;
      newCur->next = cur;
      cur = tmp;
    }
    return newHead->next;
  }
};

// Accepted
// 19/19 cases passed (47 ms)
// Your runtime beats 44.67 % of cpp submissions
// Your memory usage beats 14.7 % of cpp submissions (9.8 MB)
Algorithm