Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity.
題意：歸并k個有序的鏈表。
我的是遞歸的兩路歸并
java代碼:
class Main23 {
public ListNode mergeKLists(ListNode[] lists) {
if (lists == null || lists.length == 0) return null;
return sort(lists, 0, lists.length - 1);
}
public static ListNode sort(ListNode[] lists, int left, int right) {
if (left >= right) return lists[left];
int center = left + (right - left) / 2;
ListNode node = sort(lists, left, center);
ListNode node2 = sort(lists, center + 1, right);
return merage(node, node2);
}
private static ListNode merage(ListNode l1, ListNode l2) {
ListNode head = new ListNode(0);
ListNode first = head;
while (l1 != null && l2 != null) {
if (l1.val <= l2.val) {
first.next = l1;
l1 = l1.next;
} else {
first.next = l2;
l2 = l2.next;
}
first = first.next;
}
if (l1 == null) first.next = l2;
if (l2 == null) first.next = l1;
return head.next;
}
}
