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Commit e45ec2e

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JAVA 知识体系
1 parent 2e8d719 commit e45ec2e

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5 files changed

+148
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‎README.md‎

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@@ -100,6 +100,7 @@
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- [画一个线程的生命周期状态图。](https://blog.csdn.net/houbin0912/article/details/77969563)
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- sleep和wait的区别。
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- sleep和sleep(0)的区别。
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- [Java 各种锁的小结](https://mp.weixin.qq.com/s/_xazrXa8MBYaz2WaX6BNew)
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- [Lock与Synchronized的区别 。](https://blog.csdn.net/javazejian/article/details/75043422)
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- [synchronized的原理是什么](https://blog.csdn.net/javazejian/article/details/72828483)
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- [量级锁,可重入锁,公平锁,非公平锁,乐观锁,悲观锁。](https://www.toutiao.com/i6630764198357893646/)

‎src/main/java/com/algorithm/study/demo/datastructure/heap/TopkCount.java‎

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@@ -17,7 +17,7 @@ public class TopkCount {
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* @param k
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* @return
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*/
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public static int[] topk(int[] data, int k) {
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public static int topk(int[] data, int k) {
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PriorityQueue<Integer> queue = new PriorityQueue<>(k);
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for (int i = 0; i < data.length; i++) {
@@ -32,18 +32,69 @@ public static int[] topk(int[] data, int k) {
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}
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}
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}
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return queue.peek();
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}
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/**
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* 手动实现堆然后查找topK
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* @param nums
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* @param k
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* @return
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*/
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public static int findKthLargest(int[] nums, int k) {
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//构建一个小顶堆数组
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int[] out = new int[k];
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//小顶堆元素数量
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int count = 0;
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//循环处理数组
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for (int i=0;i<nums.length;i++){
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//数组没有满之前,从下向上调整
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if(count<k){
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out[i] = nums[i];
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count++;
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down2up(out,i);
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}else{
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//数组满了以后,如果新元素大于堆顶则替换堆顶,然后从上向下调整
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if(nums[i]>out[0]){
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out[0] = nums[i];
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up2down(out,0);
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}
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}
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}
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return out[0];
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}
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int[] result = new int[k];
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int index = 0;
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// 遍历完成后,小顶堆的数据就为需要求得的topk的数据
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while (!queue.isEmpty()) {
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result[index++] = queue.poll();
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//从下向上调整,构建小顶堆
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public static void down2up(int[] nums,int i){
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int parent = (i-1)/2;
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while(parent>=0&&nums[i]<nums[parent]){
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swap(nums,i,parent);
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i = parent;
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parent = (i-1)/2;
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}
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}
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//从上向下调整,构建小顶堆
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public static void up2down(int[] nums,int p){
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while(true){
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int left = 2*p+1;
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int right = 2*p+2;
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int minpos = p;
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if(left<nums.length&&nums[left]<nums[p]) minpos=left;
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if(right<nums.length&&nums[right]<nums[minpos]) minpos=right;
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if(minpos==p) break;
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swap(nums,p,minpos);
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p = minpos;
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}
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}
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return result;
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private static void swap(int[] nums, int i, int parent) {
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int tmp = nums[i];
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nums[i] = nums[parent];
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nums[parent] = tmp;
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}
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public static void main(String[] args) {
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System.out.println(JSON.toJSONString(topk(new int[]{1,2,3,4,5},2)));
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System.out.println(findKthLargest(new int[]{1,2,3,4,5},2));
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}
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}
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package com.algorithm.study.demo.datastructure.linear;
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/**
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* 链表数据结构
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* @Author: liuxun
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* @CreateDate: 2019年2月12日 下午3:43
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* @Version: 1.0
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*/
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public class ListNode {
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int val;
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ListNode next;
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public ListNode(int val){
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this.val=val;
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}
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}

‎src/main/java/com/algorithm/study/demo/datastructure/linear/MLinkList.java‎

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*/
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public class MLinkList<E> {
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// 定义一个内部类Node,代表链表的节点
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private class Node {
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public class Node {
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private E value;// 保存数据
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private Node next;// 指向下个节点的引用
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@@ -214,17 +214,17 @@ public void reverseLinkedList(){
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System.out.println("反转完毕");
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}
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public static void main(String[] args) {
219-
MLinkList mLinkList=new MLinkList();
220-
mLinkList.add("a");
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mLinkList.add("b");
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mLinkList.add("c");
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mLinkList.add("d");
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MLinkList<Integer> mLinkList=new MLinkList();
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mLinkList.add(4);
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mLinkList.add(1);
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mLinkList.add(8);
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mLinkList.add(4);
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mLinkList.add(5);
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// System.out.println(mLinkList.toString());
225225
// mLinkList.delete("b");
226-
mLinkList.delete(0);
227-
System.out.println(mLinkList.size);
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// mLinkList.delete(0);
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// System.out.println(mLinkList.size);
228228
// mLinkList.reverseLinkedList();
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System.out.println(mLinkList.toString());
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package com.algorithm.study.demo.datastructure.linear;
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import org.omg.PortableInterceptor.INACTIVE;
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import java.util.Arrays;
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import java.util.HashMap;
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import java.util.Map;
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/**
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* @Author: liuxun
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* @CreateDate: 2019年2月12日 下午3:43
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* @Version: 1.0
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*/
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public class Solution {
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public static ListNode detectCycle(ListNode head) {
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ListNode temp=head;
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ListNode temp2=head;
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while(temp!=null && temp.next.next!=null){
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temp2=temp2.next.next;
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temp=temp.next;
21+
if (temp==temp2){
22+
ListNode q = head;
23+
while(temp2!=q){
24+
temp2=temp2.next;
25+
q=q.next;
26+
}
27+
return q;
28+
}
29+
}
30+
return null;
31+
}
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33+
public static void main(String[] args) {
34+
ListNode head=new ListNode(3);
35+
ListNode head0=new ListNode(1);
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ListNode head1=new ListNode(2);
38+
ListNode head2=new ListNode(-4);
39+
40+
head.next=head0;
41+
head0.next=head1;
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head1.next=head2;
43+
head2.next=head1;
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// head1.next=head2;
45+
// head2.next=head3;
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// head3.next=head1;
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ListNode c=Solution.detectCycle(head);
48+
System.out.println(c==null?-1:1);
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50+
51+
}
52+
public boolean containsDuplicate(int[] nums) {
53+
if(nums==null || nums.length<2){
54+
return false;
55+
}
56+
Arrays.sort(nums);
57+
for(int i=0;i<nums.length-1;i++){
58+
if (nums[i]==nums[i+1]){
59+
return true;
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}
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}
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return false;
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}
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}

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