From 84f1b5fa8352205ca8930d58c9b07961fe235820 Mon Sep 17 00:00:00 2001 From: fanxb Date: Wed, 23 Feb 2022 11:24:00 +0800 Subject: [PATCH] add --- 5.leetcode/src/com/fanxb/common/ListNode.java | 18 +++ 5.leetcode/src/com/fanxb/common/Q23.java | 118 ++++++++++++++++++ 5.leetcode/src/com/fanxb/common/Q25.java | 56 +++++++++ 3 files changed, 192 insertions(+) create mode 100644 5.leetcode/src/com/fanxb/common/ListNode.java create mode 100644 5.leetcode/src/com/fanxb/common/Q23.java create mode 100644 5.leetcode/src/com/fanxb/common/Q25.java diff --git a/5.leetcode/src/com/fanxb/common/ListNode.java b/5.leetcode/src/com/fanxb/common/ListNode.java new file mode 100644 index 0000000..93a4750 --- /dev/null +++ b/5.leetcode/src/com/fanxb/common/ListNode.java @@ -0,0 +1,18 @@ +package com.fanxb.common; + +public class ListNode { + int val; + ListNode next; + + public ListNode() { + } + + public ListNode(int val) { + this.val = val; + } + + public ListNode(int val, ListNode next) { + this.val = val; + this.next = next; + } +} diff --git a/5.leetcode/src/com/fanxb/common/Q23.java b/5.leetcode/src/com/fanxb/common/Q23.java new file mode 100644 index 0000000..778fbac --- /dev/null +++ b/5.leetcode/src/com/fanxb/common/Q23.java @@ -0,0 +1,118 @@ +package com.fanxb.common; + +import java.util.*; +import java.util.stream.Collectors; + +public class Q23 { + public static class ListNode { + int val; + ListNode next; + + ListNode() { + } + + ListNode(int val) { + this.val = val; + } + + ListNode(int val, ListNode next) { + this.val = val; + this.next = next; + } + } + + public ListNode mergeKLists(ListNode[] lists) { + PriorityQueue queue = new PriorityQueue<>(Comparator.comparingInt(a -> a.val)); + queue.addAll(Arrays.stream(lists).filter(Objects::nonNull).collect(Collectors.toList())); + if (queue.isEmpty()) { + return null; + } + ListNode res = queue.poll(), temp = res; + while (!queue.isEmpty()) { + if (temp.next != null) { + queue.add(temp.next); + } + temp.next = queue.poll(); + temp = temp.next; + } + return res; + } + + /** + * 依次归并 + */ + public ListNode so1(ListNode[] lists) { + List listNodeList = Arrays.stream(lists).filter(Objects::nonNull).collect(Collectors.toList()); + if (listNodeList.isEmpty()) { + return null; + } + ListNode res = listNodeList.get(0); + for (int i = 1; i < listNodeList.size(); i++) { + //依次和第i合并 + ListNode tempRes = new ListNode(), temp = tempRes; + ListNode cur = listNodeList.get(i); + while (res != null && cur != null) { + if (res.val < cur.val) { + temp.next = res; + res = res.next; + } else { + temp.next = cur; + cur = cur.next; + } + temp = temp.next; + } + //接上剩下的部分 + temp.next = res == null ? cur : res; + //临时结果 + res = tempRes.next; + } + return res; + } + + public ListNode so2(ListNode[] lists) { + List listNodeList = Arrays.stream(lists).filter(Objects::nonNull).collect(Collectors.toList()); + int n = listNodeList.size(); + if (n == 0) { + return null; + } + while (n > 1) { + int count = 0; + for (int i = 0; i + 1 < n; i += 2, count++) { + ListNode a = listNodeList.get(i), b = listNodeList.get(i + 1), head = new ListNode(), temp = head; + while (a != null && b != null) { + if (a.val < b.val) { + temp.next = a; + a = a.next; + } else { + temp.next = b; + b = b.next; + } + temp = temp.next; + } + temp.next = a == null ? b : a; + listNodeList.set(count, head.next); + } + //如果为奇数，要把最后一个落单的放到count上 + if (n % 2 != 0) { + listNodeList.set(count++, listNodeList.get(n - 1)); + } + //新的链表数量为count + n = count; + } + return listNodeList.get(0); + } + + public static void main(String[] args) { + ListNode a = new ListNode(1); + a.next = new ListNode(4); + a.next.next = new ListNode(5); + ListNode b = new ListNode(1); + b.next = new ListNode(3); + b.next.next = new ListNode(4); + ListNode c = new ListNode(2); + c.next = new ListNode(6); +// new Q23().mergeKLists(new ListNode[]{a, b, c}); +// new Q23().so1(new ListNode[]{a, b, c}); + new Q23().so2(new ListNode[]{a, b}); + } +} diff --git a/5.leetcode/src/com/fanxb/common/Q25.java b/5.leetcode/src/com/fanxb/common/Q25.java new file mode 100644 index 0000000..a999912 --- /dev/null +++ b/5.leetcode/src/com/fanxb/common/Q25.java @@ -0,0 +1,56 @@ +package com.fanxb.common; + +public class Q25 { + public ListNode reverseKGroup(ListNode head, int k) { + ListNode res = new ListNode(), index = head; + res.next = head; + int count = 0; + //left:开始翻转节点的父节点 + //right:结束翻转的节点 + ListNode beforeL = res, l = beforeL.next, r, afterR; + while (index != null) { + if (++count == k) { + //进行翻转 + r = index; + afterR = index.next; + reverse(l, count); + index = l; + //处理头尾节点关系 + l.next = afterR; + beforeL.next = r; + //进行下一轮循环 + beforeL = index; + l = index.next; + count = 0; + } + index = index.next; + } + return res.next; + } + + /** + * 翻转start后的n个节点 + * + * @param start + * @param n + */ + private void reverse(ListNode start, int n) { + //反转节点 + ListNode prev = null; + for (int i = 0; i < n; i++) { + ListNode next = start.next; + start.next = prev; + prev = start; + start = next; + } + } + + public static void main(String[] args) { + ListNode node = new ListNode(1); + node.next = new ListNode(2); + node.next.next = new ListNode(3); + node.next.next.next = new ListNode(4); + node.next.next.next.next = new ListNode(5); + new Q25().reverseKGroup(node, 3); + } +}