Merge K Sorted Lists
You are given an array of k
linked-lists lists
, each linked-list is sorted in ascending order.
Merge all the linked-lists into one sorted linked-list and return it.
Example 1: Input : lists = [[1,4,5],[1,3,4],[2,6]] Output : [1,1,2,3,4,4,5,6]
Example 2 : Input : lists = [ ] Output : [ ]
Example 3 : Input : lists = [[ ]] Output : [ ]
์๋ฃ๊ตฌ์กฐ : ์ฐ์ ์์ ํ(=์ ๋ ฌ), ๋งํฌ๋๋ฆฌ์คํธ ์ด์ฉ
์๊ณ ๋ฆฌ์ฆ 1. ์๋ฃ๊ตฌ์กฐ ์์ฑ 2. ์ฐ์ ์์ ํ(์ค๋ฆ์ฐจ์ ์ ๋ ฌ)์ ๋ฐ์ดํฐ ๋ฃ๋๋ค. 3. ํ์์ ๋ฐ์ดํฐ ๋นผ๋ฉด์ ์ ๋ต๋ฆฌ์คํธ์ ๋ฃ๋๋ค.//+ํ์์ ๋นผ๋ ค๋ ๋ฐ์ดํฐ์ ๋ค์ ๋ ธ๋๊ฐ Null์ด ์๋๋ฉด node.next๋ฅผ ํ์ ๋ฃ๋๋ค.
์๊ณ ๋ฆฌ์ฆ์ Java๋ก ๊ตฌํ
/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode() {}
* ListNode(int val) { this.val = val; }
* ListNode(int val, ListNode next) { this.val = val; this.next = next; }
* }
*/
class Solution {
public ListNode mergeKLists(ListNode[] lists) {
//1.์๋ฃ๊ตฌ์กฐ ์์ฑ
ListNode dummyHead = new ListNode(0);
ListNode p = dummyHead;
PriorityQueue<ListNode> queue = new PriorityQueue<ListNode>(Comp);
//2.ํ์ ๋ฐ์ดํฐ ๋ด๊ธฐ
for(ListNode node : lists) {
if(node != null) {
queue.offer(node);
}
}
//3.ํ์์ ๋ฐ์ดํฐ ๋นผ๋ฉด์ ์ ๋ต ๋ฆฌ์คํธ์ ๋ด๊ธฐ
while(!queue.isEmpty()) {//๋น์ง ์๋ ๋์๋ง(๋ฐ์ดํฐ๊ฐ ์์ ๋๋ง).
ListNode node = queue.poll();
p.next = node;
p = p.next;
if(node.next != null) {
queue.offer(node);
}
}
return dummyHead.next;
}
Comparator<ListNode> Comp = new Comparator<ListNode>(){
public int compare(ListNode l1, ListNode l2) {
return l1.val - l2.val;//ascending order
}
};
}
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