diff --git a/Week_01/id_42/LeeCode_83_042.java b/Week_01/id_42/LeeCode_83_042.java
new file mode 100644
index 00000000..d212686d
--- /dev/null
+++ b/Week_01/id_42/LeeCode_83_042.java
@@ -0,0 +1,38 @@
+package list;
+
+public class LeeCode_83_042 {
+
+	/*
+	 * Definition for singly-linked list.
+	 * */
+
+    public ListNode deleteDuplicates(ListNode head) {
+        ListNode stubNode = head;    
+        if(head ==null){
+            return null;
+        }else{
+            ListNode ptemp= head.next;
+            int stub = head.val;
+            while(ptemp!=null){
+                if(stub == ptemp.val){
+                    head.next = ptemp.next;
+                }else{
+                    stub = ptemp.val;
+                    head = head.next;               
+                }           
+                ptemp = ptemp.next;
+                if(ptemp!=null){
+                    System.out.println(ptemp.val); 
+                }
+
+
+            }
+            return stubNode;
+        }
+    }
+    
+    public static void main(String[] args){
+    	
+    }
+}
+
diff --git a/Week_01/id_42/LeeCode_905_042.java b/Week_01/id_42/LeeCode_905_042.java
new file mode 100644
index 00000000..7ed0a2dd
--- /dev/null
+++ b/Week_01/id_42/LeeCode_905_042.java
@@ -0,0 +1,43 @@
+package array;
+
+public class LeeCode_905_042 {
+    public static int[] sortArrayByParity(int[] A) {
+        
+		int oddSize = 0;
+		
+		for(int i =0;i< A.length; i++){
+			if(A[i]%2 !=0){
+				oddSize++;
+			}
+		}
+		int start =0;
+		int end = A.length-1;
+		
+		if(oddSize > 0 && oddSize < A.length){
+			while(oddSize >0 || start< end){
+				if(A[start]%2 !=0){
+					oddSize--;
+					for(int j =end; j> start; j--){
+						if((A[j]%2) == 0){
+							int temp = A[start];
+							A[start] = A[j];
+							A[j]= temp;							
+							end = j-1;
+							break;
+						}	
+					}
+				}
+				start ++;
+			}
+					
+		}
+		return A;
+    }
+    public static void main(String[] args){
+    	int[] A ={1,2,3,4,5,6,7,8,9,10};
+    	LeeCode_905_042.sortArrayByParity(A);
+    	for(int i =0; i< A.length ;i++){
+    		System.out.println(A[i]);
+    	}
+    }
+}
diff --git a/Week_02/id_42/NOTE.md b/Week_02/id_42/NOTE.md
index c684e62f..c606e380 100644
--- a/Week_02/id_42/NOTE.md
+++ b/Week_02/id_42/NOTE.md
@@ -1 +1,4 @@
-# 学习笔记
\ No newline at end of file
+# 学习笔记
+无感想，想学习套路，发现基础不牢，把自己套进去了。接着做题吧。
+面试别人的时候，用了链表的题目，候选人没有做出来，
+自己调试代码的时候，死循环了。
diff --git a/Week_02/id_42/leecoce_692_042.java b/Week_02/id_42/leecoce_692_042.java
new file mode 100644
index 00000000..5d737dc6
--- /dev/null
+++ b/Week_02/id_42/leecoce_692_042.java
@@ -0,0 +1,17 @@
+class leecode_692_042{
+    List<Integer> list = new ArrayList<Integer>();
+    public int findSecondMinimumValue(TreeNode root) {
+        if (root == null) return -1;
+        if (!list.contains(root.val)) list.add(root.val);
+        findSecondMinimumValue(root.left);
+        findSecondMinimumValue(root.right);
+        Collections.sort(list);
+        if (list.size() <= 1) {
+            return -1;
+        } else {
+            return list.get(1);
+        }
+
+    }
+
+}
\ No newline at end of file
diff --git a/Week_02/id_42/leecode_671_042.java b/Week_02/id_42/leecode_671_042.java
new file mode 100644
index 00000000..f27e0869
--- /dev/null
+++ b/Week_02/id_42/leecode_671_042.java
@@ -0,0 +1,44 @@
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.TreeMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+
+class leecode_671_042 {
+    public List<String> topKFrequent(String[] words, int k) {
+        TreeMap<String,Integer> wordsCount = new TreeMap<String,Integer>();
+        // statistic
+        for(String word:words){
+            if(wordsCount.containsKey(word)){
+                int count = wordsCount.get(word);
+                count++;
+                wordsCount.put(word, count);
+            }else{
+                wordsCount.put(word, 1);
+            }
+
+        }
+
+        //sort
+
+        List<Map.Entry<String,Integer>> list  = new ArrayList<Map.Entry<String,Integer>>(wordsCount.entrySet());
+        Collections.sort(list, new Comparator<Map.Entry<String,Integer>>() {
+            public int compare(Entry<String, Integer> o1,
+                               Entry<String, Integer> o2) {
+                return o2.getValue().compareTo(o1.getValue());
+            }
+
+        });
+
+        List<String> result = new  ArrayList<String>();
+
+        for(int i=0;i<k;i++){
+            result.add(list.get(i).getKey());
+        }
+
+        return result;
+
+    }
+}
\ No newline at end of file
diff --git a/Week_03/id_42/NOTE.md b/Week_03/id_42/NOTE.md
index c684e62f..0562a4d4 100644
--- a/Week_03/id_42/NOTE.md
+++ b/Week_03/id_42/NOTE.md
@@ -1 +1,2 @@
-# 学习笔记
\ No newline at end of file
+# 学习笔记
+这周的学习开始吃力，涉及到不太会的东西了。
\ No newline at end of file
diff --git a/Week_03/id_42/leecode_703_042.java b/Week_03/id_42/leecode_703_042.java
new file mode 100644
index 00000000..73ea70c0
--- /dev/null
+++ b/Week_03/id_42/leecode_703_042.java
@@ -0,0 +1,27 @@
+import java.util.PriorityQueue;
+
+class leecode_671_042 {
+    class KthLargest {
+        final PriorityQueue<Integer> q;
+        final int k;
+
+        public KthLargest(int k, int[] nums) {
+            this.k = k;
+            q = new PriorityQueue<Integer>(k);
+            for (int i : nums) {
+                add(i);
+            }
+        }
+
+        public int add(int val) {
+            if (q.size() < k) {
+                q.offer(val);
+
+            } else if (q.peek() < val) {
+                q.poll();
+                q.offer(val);
+            }
+            return q.peek();
+        }
+    }
+}
\ No newline at end of file
diff --git a/Week_03/id_42/leecode_997_042.java b/Week_03/id_42/leecode_997_042.java
new file mode 100644
index 00000000..1fbae7e1
--- /dev/null
+++ b/Week_03/id_42/leecode_997_042.java
@@ -0,0 +1,14 @@
+class leecode_997_042 {
+    public int findJudge(int N, int[][] trust) {
+        int[] index = new int[N+1];
+        for(int[] t : trust){
+            index[t[0]] = -1;
+            if(index[t[1]] != -1) index[t[1]]++;
+        }
+        for(int i = 1; i <= N; i++){
+            if(index[i] == N-1) return i;
+        }
+
+        return -1;
+    }
+}
\ No newline at end of file