<?xml version="1.0" encoding="utf-8" ?><rss version="2.0"><channel><title><![CDATA[m0_50996152的博客]]></title><description><![CDATA[]]></description><link>https://blog.youkuaiyun.com/m0_50996152</link><language>zh-cn</language><generator>https://blog.youkuaiyun.com/</generator><copyright><![CDATA[Copyright &copy; m0_50996152]]></copyright><item><title><![CDATA[sql五十题中前25题的非重点]]></title><link>https://blog.youkuaiyun.com/m0_50996152/article/details/124649091</link><guid>https://blog.youkuaiyun.com/m0_50996152/article/details/124649091</guid><author>m0_50996152</author><pubDate>Tue, 10 May 2022 16:01:27 +0800</pubDate><description><![CDATA[3、查询所有学生的学号、姓名、选课数、总成绩（不重要）


#连接查询后是假想的表，执行时候还是各顾各的
SELECT a.s_id, a.s_name, COUNT(b.c_id) AS `选课数`, SUM(b.s_score) AS `总成绩`
FROM student AS a JOIN score AS b ON a.s_id = b.s_id
GROUP BY a.s_id



4、查询姓“张”的老师的个数（不重要）


SELECT COUNT(t_name) AS `个数`
FROM t.]]></description><category></category></item><item><title><![CDATA[sql五十题中前25题的重点]]></title><link>https://blog.youkuaiyun.com/m0_50996152/article/details/124648823</link><guid>https://blog.youkuaiyun.com/m0_50996152/article/details/124648823</guid><author>m0_50996152</author><pubDate>Tue, 10 May 2022 16:01:14 +0800</pubDate><description><![CDATA[1.查询课程编号为“01”的课程比“02”的课程成绩高的所有学生的学号（重点）


SELECT a.s_id FROM 
	#多加括号错了,()起来重新命名也不对，连接查询过后没法设置成一个新表，是假象的新表
	(SELECT s_id, c_id,s_score FROM score WHERE c_id = '01') AS a
	JOIN 
	(SELECT s_id, c_id,s_score FROM score WHERE c_id = '02') AS b
	ON a.s_id = b.s_]]></description><category></category></item><item><title><![CDATA[剑指（五题）]]></title><link>https://blog.youkuaiyun.com/m0_50996152/article/details/124677857</link><guid>https://blog.youkuaiyun.com/m0_50996152/article/details/124677857</guid><author>m0_50996152</author><pubDate>Mon, 09 May 2022 23:12:03 +0800</pubDate><description><![CDATA[/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public ListNode reverseList(ListNode head) {
        if (head == null) return ...]]></description><category></category></item><item><title><![CDATA[剑指（五题）]]></title><link>https://blog.youkuaiyun.com/m0_50996152/article/details/124646314</link><guid>https://blog.youkuaiyun.com/m0_50996152/article/details/124646314</guid><author>m0_50996152</author><pubDate>Sun, 08 May 2022 12:20:45 +0800</pubDate><description><![CDATA[class Solution {
    public int lengthOfLongestSubstring(String s) {
        if (s.length() == 0) return 0;
        int len = s.length();
        int max = 1;
        for (int i = 0; i &lt; len; i++) {
            char ch = s.charAt(i);
            /...]]></description><category></category></item><item><title><![CDATA[剑指（五道）]]></title><link>https://blog.youkuaiyun.com/m0_50996152/article/details/124609863</link><guid>https://blog.youkuaiyun.com/m0_50996152/article/details/124609863</guid><author>m0_50996152</author><pubDate>Fri, 06 May 2022 14:41:01 +0800</pubDate><description><![CDATA[class Solution {
    public int majorityElement(int[] nums) {
        
        Map&lt;Integer, Integer&gt; map = new HashMap&lt;&gt;();
        //k代表数字，v代表出现的次数
        for (int i = 0; i &lt; nums.length; i++) {
            map.put(nums[i], map.getOr...]]></description><category></category></item><item><title><![CDATA[力扣关于数据库的题目(12道)]]></title><link>https://blog.youkuaiyun.com/m0_50996152/article/details/124596286</link><guid>https://blog.youkuaiyun.com/m0_50996152/article/details/124596286</guid><author>m0_50996152</author><pubDate>Thu, 05 May 2022 23:32:41 +0800</pubDate><description><![CDATA[#连接后这两个就是一个表了
select firstName, lastName, city, state
from Person left join Address
on Person.PersonId = Address.PersonId;

select p.firstName, p.lastName, a.city, a.state
from Person as p left join Address as a
on p.PersonId = a.PersonId;









...]]></description><category></category></item><item><title><![CDATA[剑指（五题）]]></title><link>https://blog.youkuaiyun.com/m0_50996152/article/details/124587823</link><guid>https://blog.youkuaiyun.com/m0_50996152/article/details/124587823</guid><author>m0_50996152</author><pubDate>Thu, 05 May 2022 14:18:04 +0800</pubDate><description><![CDATA[/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    public int[] levelOrder(TreeNode root) {
        //bfs...]]></description><category></category></item><item><title><![CDATA[剑指（五题）]]></title><link>https://blog.youkuaiyun.com/m0_50996152/article/details/124579465</link><guid>https://blog.youkuaiyun.com/m0_50996152/article/details/124579465</guid><author>m0_50996152</author><pubDate>Wed, 04 May 2022 22:50:10 +0800</pubDate><description><![CDATA[// class Solution {
//     public int[] exchange(int[] nums) {
//         int[] res = new int[nums.length];
//         int t = 0;
//         for (int i = 0; i &lt; nums.length; i++) {
//             if (!method(nums[i])) {
//                 res[t++] = ...]]></description><category></category></item><item><title><![CDATA[5.3剑指6道题]]></title><link>https://blog.youkuaiyun.com/m0_50996152/article/details/124554351</link><guid>https://blog.youkuaiyun.com/m0_50996152/article/details/124554351</guid><author>m0_50996152</author><pubDate>Tue, 03 May 2022 13:49:44 +0800</pubDate><description><![CDATA[//和整数拆分是一样的
class Solution {
    public int cuttingRope(int n) {
        //dp[i]代表的是i拆分获得的最大值
        int[] dp = new int[n + 1];
        dp[2] = 1;
        for (int i = 3; i &lt; n + 1; i++) {
            //枚举所有情况就行，不用写成&lt;=i - j排除情况
            for ...]]></description><category></category></item><item><title><![CDATA[5.2剑指开刷（前10）]]></title><link>https://blog.youkuaiyun.com/m0_50996152/article/details/124542365</link><guid>https://blog.youkuaiyun.com/m0_50996152/article/details/124542365</guid><author>m0_50996152</author><pubDate>Mon, 02 May 2022 16:20:54 +0800</pubDate><description><![CDATA[class Solution {
    public int findRepeatNumber(int[] nums) {
        int len = nums.length;
        Map&lt;Integer, Integer&gt; map = new HashMap&lt;&gt;();
        for (int i = 0; i &lt; len; i++) {
            if (map.containsKey(nums[i])) {
       ...]]></description><category></category></item><item><title><![CDATA[hot100相关（六题一组记录）]]></title><link>https://blog.youkuaiyun.com/m0_50996152/article/details/124503914</link><guid>https://blog.youkuaiyun.com/m0_50996152/article/details/124503914</guid><author>m0_50996152</author><pubDate>Fri, 29 Apr 2022 20:42:25 +0800</pubDate><description><![CDATA[class Solution {
        public int search(int[] nums, int target) {
            int len = nums.length;
            int left = 0;
            int right = len - 1;
            int res = 0;
            while (left &lt;= right) {
                int mid = ...]]></description><category></category></item><item><title><![CDATA[hot100相关（五题一组记录）]]></title><link>https://blog.youkuaiyun.com/m0_50996152/article/details/124503797</link><guid>https://blog.youkuaiyun.com/m0_50996152/article/details/124503797</guid><author>m0_50996152</author><pubDate>Fri, 29 Apr 2022 20:34:19 +0800</pubDate><description><![CDATA[// class Solution {
//     public int hammingDistance(int x, int y) {
//         return Integer.bitCount(x ^ y);
//     }
// }

// class Solution {
//     public int hammingDistance(int x, int y) {
//         int s = x ^ y;//自动补全高位开始异或运算(相同为0，不同为1)
/...]]></description><category></category></item><item><title><![CDATA[hot100（五题一组记录）]]></title><link>https://blog.youkuaiyun.com/m0_50996152/article/details/124503620</link><guid>https://blog.youkuaiyun.com/m0_50996152/article/details/124503620</guid><author>m0_50996152</author><pubDate>Fri, 29 Apr 2022 20:23:11 +0800</pubDate><description><![CDATA[/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right...]]></description><category></category></item><item><title><![CDATA[hot100补充(6题一组)]]></title><link>https://blog.youkuaiyun.com/m0_50996152/article/details/123777855</link><guid>https://blog.youkuaiyun.com/m0_50996152/article/details/123777855</guid><author>m0_50996152</author><pubDate>Sun, 27 Mar 2022 17:57:16 +0800</pubDate><description><![CDATA[public class Solution {
    public boolean wordBreak(String s, List&lt;String&gt; wordDict) {
        // 可以类比于背包问题
        Set&lt;String&gt; wordDictSet = new HashSet(wordDict);
        // dp[i] 表示 s 中以 i - 1 结尾的字符串是否可被 wordDict 拆分
        boolean[] dp ...]]></description><category></category></item><item><title><![CDATA[hot100补充(5题一组)]]></title><link>https://blog.youkuaiyun.com/m0_50996152/article/details/123755330</link><guid>https://blog.youkuaiyun.com/m0_50996152/article/details/123755330</guid><author>m0_50996152</author><pubDate>Sat, 26 Mar 2022 14:25:16 +0800</pubDate><description><![CDATA[//f(i)表示以i为根的二叉树的搜索树个数，所以n的全部的搜索树个数G(n)
// G(n)=f(1)+f(2)+f(3)+f(4)+...+f(n)

// 当 i 为根节点时，其左子树节点个数为 i-1 个，右子树节点为 n-i，则左子节点二叉排序树的个数*右子节点二叉排序树的个数就是当i为根节点时候二叉排序树的个数
// f(i) = G(i−1)∗G(n−i)

// 综合两个公式可以得到 卡特兰数 公式
//G(n)=G(0)∗G(n−1)+G(1)∗(n−2)+...+G(n−1)...]]></description><category></category></item><item><title><![CDATA[hot100补充（5道题目一组）]]></title><link>https://blog.youkuaiyun.com/m0_50996152/article/details/123735678</link><guid>https://blog.youkuaiyun.com/m0_50996152/article/details/123735678</guid><author>m0_50996152</author><pubDate>Fri, 25 Mar 2022 14:53:52 +0800</pubDate><description><![CDATA[//这么简单得题目，别强迫症了啊，无所谓啊，哎

//3.21记住只要是题目都很奇妙，不奇妙得没法出，大胆写
//就是两种变化从1234到1243这是第一类，直接倒数两个得交换
//第二种变换1243到1324这种，当前值和后面比当前大得排序后最小得交换。
//因为这个题目是只找当前传入的下一个就行
class Solution {
    public void nextPermutation(int[] nums) {
        int len = nums.length;
     ...]]></description><category></category></item><item><title><![CDATA[初步了解贪心算法]]></title><link>https://blog.youkuaiyun.com/m0_50996152/article/details/122500301</link><guid>https://blog.youkuaiyun.com/m0_50996152/article/details/122500301</guid><author>m0_50996152</author><pubDate>Fri, 14 Jan 2022 19:10:12 +0800</pubDate><description><![CDATA[class Solution {
    public int findContentChildren(int[] g, int[] s) {
        Arrays.sort(g);
        Arrays.sort(s);
        int gLen = g.length;
        int sLen = s.length;
        int i = 0;
        int j = 0;
        int count = 0;
   ...]]></description><category></category></item><item><title><![CDATA[递归和回溯算法模板，区别以及相关题目]]></title><link>https://blog.youkuaiyun.com/m0_50996152/article/details/122448909</link><guid>https://blog.youkuaiyun.com/m0_50996152/article/details/122448909</guid><author>m0_50996152</author><pubDate>Wed, 12 Jan 2022 11:33:45 +0800</pubDate><description><![CDATA[三道题套路解决递归问题 | lyl's blog (lyl0724.github.io)














public class Solution {

    List&lt;List&lt;Integer&gt;&gt; res = new ArrayList&lt;&gt;();
    //使用removeLast()必须是LinkedList
    //再说了增删肯定LinkedList更方便
    //...]]></description><category></category></item><item><title><![CDATA[二叉树第一阶段总结补充(这篇主要用的BFS)]]></title><link>https://blog.youkuaiyun.com/m0_50996152/article/details/122370146</link><guid>https://blog.youkuaiyun.com/m0_50996152/article/details/122370146</guid><author>m0_50996152</author><pubDate>Fri, 07 Jan 2022 18:35:08 +0800</pubDate><description><![CDATA[/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, Tre...]]></description><category></category></item><item><title><![CDATA[二叉树第一阶段总结(这篇主要用的BFS)]]></title><link>https://blog.youkuaiyun.com/m0_50996152/article/details/122370023</link><guid>https://blog.youkuaiyun.com/m0_50996152/article/details/122370023</guid><author>m0_50996152</author><pubDate>Fri, 07 Jan 2022 18:28:09 +0800</pubDate><description><![CDATA[/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right...]]></description><category></category></item></channel></rss>