diff --git a/code/lc11.java b/code/lc11.java
index a7f036a9db75d885f54f7c7107b2c42f73db0762..2657f381e8b169ca8cf38e3b01fb1e47c70f983a 100644
--- a/code/lc11.java
+++ b/code/lc11.java
@@ -5,6 +5,7 @@ package code;
  * 难度：Medium
  * 分类：Array, Two Pointers
  * Tips：复杂度可以为O(N), 指针往里走, 若值也小了，则面积一定不会增大。和lc42做比较
+ *      lc11, lc42, lc84
  */
 public class lc11 {
     public static void main(String[] args) {
diff --git a/code/lc146.java b/code/lc146.java
index c100a08d069b74ffd6b96e5f9d8b098df3988936..63f9d7abaec784c8e2fdaf4f47572ed6be2b2cc4 100644
--- a/code/lc146.java
+++ b/code/lc146.java
@@ -11,7 +11,7 @@ package code;
 import java.util.HashMap;
 
 public class lc146 {
-    class Node {
+    class Node {    //定义一个Node类
         int key;
         int value;
         Node pre;
@@ -25,8 +25,8 @@ public class lc146 {
     public class LRUCache {
 
         HashMap<Integer, Node> map;
-        int capicity, count;
-        Node head, tail;
+        int capicity, count;    //最大容量，当前容量
+        Node head, tail;    //头节点，尾节点
 
         public LRUCache(int capacity) {
             this.capicity = capacity;
@@ -40,7 +40,7 @@ public class lc146 {
             count = 0;
         }
 
-        public void deleteNode(Node node) {
+        public void deleteNode(Node node) { //两个方法
             node.pre.next = node.next;
             node.next.pre = node.pre;
         }
diff --git a/code/lc322.java b/code/lc322.java
index 986c2eab018cd02cbb44e021d79def8577b14c9a..8b2fb52a25be2e3fb9c7c7eb00e1feef48644c06 100644
--- a/code/lc322.java
+++ b/code/lc322.java
@@ -39,8 +39,8 @@ public class lc322 {
     public static int coinChange2(int[] coins, int amount) {
         int max = amount + 1;
         int[] dp = new int[amount + 1];
-        Arrays.fill(dp, max);
-        dp[0] = 0;
+        Arrays.fill(dp, max);   //表示无解
+        dp[0] = 0;  //dp[0]=0 不用先把零钱设为1了
         for (int i = 1; i <= amount; i++) {
             for (int j = 0; j < coins.length; j++) {
                 if (coins[j] <= i) {
@@ -48,6 +48,6 @@ public class lc322 {
                 }
             }
         }
-        return dp[amount] > amount ? -1 : dp[amount];
+        return dp[amount] > amount ? -1 : dp[amount];   //判断一下
     }
 }
diff --git a/code/lc42.java b/code/lc42.java
index e30d79fc816a28361e71d399657de17664e741aa..7d88179dc96cb5a698c95185be2ca1162a477d9a 100644
--- a/code/lc42.java
+++ b/code/lc42.java
@@ -8,7 +8,7 @@ import java.util.Stack;
  * 难度：Hard
  * 分类：Array, Two Pointers, Stack
  * 思路：三种方法:1.DP先求出来每个位置的maxleft,maxright，再遍历一遍;2.两个指针，类似lc11题的思路;3.用栈数据结构;
- * Tips：
+ * Tips：lc11, lc42, lc84
  */
 public class lc42 {
     public static void main(String[] args) {
diff --git a/code/lc84.java b/code/lc84.java
index df5eca9775c0196add243221b0dd6059f5dfb8dc..645ee0c22d2f7b641c348b1f7a68cb2cb9cda9be 100644
--- a/code/lc84.java
+++ b/code/lc84.java
@@ -10,7 +10,7 @@ import java.util.Stack;
  * 思路：两种方法：1.用dp找到边界，再遍历一遍; 2.用栈，栈内存索引，保证栈内索引对应的高度是递增的，若减了即找到了右边界，出栈开始计算。因为栈内是递增的，左边界就是上个栈内的元素。若栈为空，左边界就是-1。
  * Tips：和lc42做比较，都可以用栈或者dp来做. 很难，栈的操作很难想到.
  *       和lc42 dp作比较 和lc32栈做比较
- *       lc85
+ *       lc11, lc42, lc84
  */
 public class lc84 {
     public static void main(String[] args) {
diff --git a/readme.md b/readme.md
index 5742d87aac84694c9c7252871999d63895e765e0..56bc023939475be0a264b42eb93293231d46b6e9 100644
--- a/readme.md
+++ b/readme.md
@@ -131,6 +131,7 @@ LeetCode 指南
 | 150 [Java](./code/lc150.java)
 | 151 [Java](./code/lc151.java)
 | 152 [Java](./code/lc152.java)
+| 153 [Java](./code/lc153.java)
 | 155 [Java](./code/lc155.java)
 | 160 [Java](./code/lc160.java)
 | 162 [Java](./code/lc162.java)
@@ -144,6 +145,7 @@ LeetCode 指南
 | 190 [Java](./code/lc190.java)
 | 191 [Java](./code/lc191.java)
 | 198 [Java](./code/lc198.java)
+| 199 [Java](./code/lc199.java)
 | 200 [Java](./code/lc200.java)
 | 202 [Java](./code/lc202.java)
 | 204 [Java](./code/lc204.java)
@@ -209,6 +211,7 @@ LeetCode 指南
 | 448 [Java](./code/lc448.java)
 | 454 [Java](./code/lc454.java)
 | 461 [Java](./code/lc461.java)
+| 493 [Java](./code/lc493.java)
 | 494 [Java](./code/lc494.java)
 | 538 [Java](./code/lc538.java)
 | 543 [Java](./code/lc543.java)
@@ -227,6 +230,7 @@ LeetCode 指南
 | 771 [Java](./code/lc771.java)
 | 834 [Java](./code/lc834.java)
 | 877 [Java](./code/lc877.java)
+| 912 [Java](./code/lc912.java)
 | 921 [Java](./code/lc921.java)
 | 922 [Java](./code/lc922.java)
 | 923 [Java](./code/lc923.java)