diff --git a/Leecode/src/main/java/com/markilue/leecode/hot100/interviewHot/difference/LC_1094_CarPooling.java b/Leecode/src/main/java/com/markilue/leecode/hot100/interviewHot/difference/LC_1094_CarPooling.java
index 9c01fcb..abfd923 100644
--- a/Leecode/src/main/java/com/markilue/leecode/hot100/interviewHot/difference/LC_1094_CarPooling.java
+++ b/Leecode/src/main/java/com/markilue/leecode/hot100/interviewHot/difference/LC_1094_CarPooling.java
@@ -73,7 +73,6 @@ public class LC_1094_CarPooling {
 
     }
 
-
     //二刷
     public boolean carPooling1(int[][] trips, int capacity) {
         //本质上就是判断某一个位置上是否超过capacity
@@ -138,4 +137,32 @@ public class LC_1094_CarPooling {
         return true;
 
     }
+
+
+    public boolean carPooling3(int[][] trips, int capacity) {
+
+        //构建差分数组
+        int min = Integer.MAX_VALUE;
+        int max = Integer.MIN_VALUE;
+        int[] diff = new int[1001];
+
+        for (int[] trip : trips) {
+            if (trip[1] < min) min = trip[1];
+            if (trip[2] > max) max = trip[2];
+            diff[trip[1]] += trip[0];
+            diff[trip[2]] -= trip[0];
+        }
+
+        if (diff[min] > capacity) {
+            return false;
+        }
+        for (int i = min; i < max; i++) {
+            diff[i] += diff[i - 1];
+            if (diff[i] > capacity) {
+                return false;
+            }
+        }
+        return true;
+
+    }
 }
diff --git a/Leecode/src/main/java/com/markilue/leecode/hot100/interviewHot/difference/LC_1109_CorpFlightBookings.java b/Leecode/src/main/java/com/markilue/leecode/hot100/interviewHot/difference/LC_1109_CorpFlightBookings.java
index d6f6497..8d9c773 100644
--- a/Leecode/src/main/java/com/markilue/leecode/hot100/interviewHot/difference/LC_1109_CorpFlightBookings.java
+++ b/Leecode/src/main/java/com/markilue/leecode/hot100/interviewHot/difference/LC_1109_CorpFlightBookings.java
@@ -153,4 +153,22 @@ public class LC_1109_CorpFlightBookings {
         return diff;
 
     }
+
+    //四刷:
+    public int[] corpFlightBookings5(int[][] bookings, int n) {
+        int[] diff = new int[n];
+        for (int[] booking : bookings) {
+            diff[booking[0] - 1] += booking[2];
+            if (booking[1] < n) {
+                diff[booking[1]] -= booking[2];
+            }
+        }
+
+        //通过差分数组还原当前位置
+        for (int i = 1; i < diff.length; i++) {
+            diff[i] += diff[i - 1];
+        }
+
+        return diff;
+    }
 }
diff --git a/Leecode/src/main/java/com/markilue/leecode/hot100/interviewHot/graph/LC_207_CanFinish.java b/Leecode/src/main/java/com/markilue/leecode/hot100/interviewHot/graph/LC_207_CanFinish.java
new file mode 100644
index 0000000..c169400
--- /dev/null
+++ b/Leecode/src/main/java/com/markilue/leecode/hot100/interviewHot/graph/LC_207_CanFinish.java
@@ -0,0 +1,32 @@
+package com.markilue.leecode.hot100.interviewHot.graph;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ *@BelongsProject: Leecode
+ *@BelongsPackage: com.markilue.leecode.hot100.interviewHot.graph
+ *@Author: markilue
+ *@CreateTime: 2023-05-22  12:02
+ *@Description: TODO  力扣207  课程表:
+ *@Version: 1.0
+ */
+public class LC_207_CanFinish {
+
+    List<List<Integer>> edge;//边
+
+    //本质上就是图的深度优先搜索:检测这个图是否存在环路
+    public boolean canFinish(int numCourses, int[][] prerequisites) {
+
+        //使用一个list记录每个节点的子节点，使用dfs判断是否会回到父节点
+        for (int[] prerequisite : prerequisites) {
+            List<Integer> list = edge.get(prerequisite[0]);
+            if (list == null) list = new ArrayList<>();
+            else list.add(prerequisite[1]);//添加子节点
+        }
+
+
+        return false;
+
+    }
+}
diff --git a/Leecode/src/main/java/com/markilue/leecode/hot100/interviewHot/listnode/LC_82_DeleteDuplicatesII.java b/Leecode/src/main/java/com/markilue/leecode/hot100/interviewHot/listnode/LC_82_DeleteDuplicatesII.java
index fd580d1..88a4760 100644
--- a/Leecode/src/main/java/com/markilue/leecode/hot100/interviewHot/listnode/LC_82_DeleteDuplicatesII.java
+++ b/Leecode/src/main/java/com/markilue/leecode/hot100/interviewHot/listnode/LC_82_DeleteDuplicatesII.java
@@ -12,6 +12,7 @@ import com.markilue.leecode.listnode.ListNode;
  */
 public class LC_82_DeleteDuplicatesII {
 
+
     public ListNode deleteDuplicates(ListNode head) {
         ListNode fake = new ListNode(-101);
         fake.next = head;
@@ -52,4 +53,29 @@ public class LC_82_DeleteDuplicatesII {
 
         return fake.next;
     }
+
+    public ListNode deleteDuplicates2(ListNode head) {
+
+        ListNode fake = new ListNode();
+        fake.next = head;
+        ListNode cur = fake;
+
+        while (cur != null && cur.next != null) {
+            if (cur.next.next != null && cur.next.val == cur.next.next.val) {
+                //存在重复元素
+                ListNode temp = cur.next;
+                while (temp.next != null && temp.val == temp.next.val) {
+                    temp = temp.next;
+                }
+                cur.next = temp.next;
+            } else {
+                cur = cur.next;
+            }
+        }
+
+        return fake.next;
+
+    }
+
+
 }
diff --git a/Leecode/src/main/java/com/markilue/leecode/hot100/second/T34_75_SortColors.java b/Leecode/src/main/java/com/markilue/leecode/hot100/second/T34_75_SortColors.java
index 7ae21d8..77c29d1 100644
--- a/Leecode/src/main/java/com/markilue/leecode/hot100/second/T34_75_SortColors.java
+++ b/Leecode/src/main/java/com/markilue/leecode/hot100/second/T34_75_SortColors.java
@@ -75,4 +75,28 @@ public class T34_75_SortColors {
         }
 
     }
+
+
+    //三刷:本质就是遇见1就直接交换，遇见0需要判断一下是否移动了1
+    //但是这理论上来说不是原地排序，因为排前面的
+    public void sortColors2(int[] nums) {
+
+        int index0 = 0;
+        int index1 = 0;
+
+        for (int i = 0; i < nums.length; i++) {
+            if (nums[i] == 0) {
+                swap(nums, index0, i);
+                if (index0 < index1) swap(nums, index1, i);//把1交换在前面去了,需要交换回来，但是这样1就不是原地排序了
+                index0++;
+                index1++;
+            } else if (nums[i] == 1) {
+                swap(nums, index1, i);
+                index1++;
+            }
+
+        }
+
+
+    }
 }
diff --git a/Leecode/src/main/java/com/markilue/leecode/hot100/second/T49_124_MaxPathSum.java b/Leecode/src/main/java/com/markilue/leecode/hot100/second/T49_124_MaxPathSum.java
index 086b403..2f7e356 100644
--- a/Leecode/src/main/java/com/markilue/leecode/hot100/second/T49_124_MaxPathSum.java
+++ b/Leecode/src/main/java/com/markilue/leecode/hot100/second/T49_124_MaxPathSum.java
@@ -81,4 +81,22 @@ public class T49_124_MaxPathSum {
         return Math.max(leftMax, rightMax) + root.val;
     }
 
+
+    public int maxPathSum2(TreeNode root) {
+        findMax1(root);
+        return maxSum;
+    }
+
+    //返回要当前节点的最大值
+    public int findMax1(TreeNode root) {
+        if (root == null) {
+            return 0;
+        }
+        int left = Math.max(findMax1(root.left), 0);
+        int right = Math.max(findMax1(root.right), 0);
+
+        maxSum = Math.max(left + right + root.val, maxSum);
+        return Math.max(left, right) + root.val;
+
+    }
 }
diff --git a/Leecode/src/main/java/com/markilue/leecode/hot100/second/T53_141_HasCycle.java b/Leecode/src/main/java/com/markilue/leecode/hot100/second/T53_141_HasCycle.java
index 929adab..5963972 100644
--- a/Leecode/src/main/java/com/markilue/leecode/hot100/second/T53_141_HasCycle.java
+++ b/Leecode/src/main/java/com/markilue/leecode/hot100/second/T53_141_HasCycle.java
@@ -47,4 +47,17 @@ public class T53_141_HasCycle {
         return false;
 
     }
+
+    public boolean hasCycle2(ListNode head) {
+        ListNode fast = head;
+        ListNode slow = head;
+
+        while (fast != null && fast.next != null) {
+            fast = fast.next.next;
+            slow = slow.next;
+            if (fast == slow) return true;
+        }
+
+        return false;
+    }
 }
diff --git a/Leecode/src/main/java/com/markilue/leecode/hot100/second/T55_146_LRUCache.java b/Leecode/src/main/java/com/markilue/leecode/hot100/second/T55_146_LRUCache.java
index 1642121..873a1bd 100644
--- a/Leecode/src/main/java/com/markilue/leecode/hot100/second/T55_146_LRUCache.java
+++ b/Leecode/src/main/java/com/markilue/leecode/hot100/second/T55_146_LRUCache.java
@@ -1,8 +1,8 @@
 package com.markilue.leecode.hot100.second;
 
 
-
 import java.util.HashMap;
+import java.util.Map;
 
 /**
  *@BelongsProject: Leecode
@@ -47,7 +47,7 @@ public class T55_146_LRUCache {
                 Node node = deleteTail();
                 map.remove(node.key);
             }
-            Node node = new Node(key,value);
+            Node node = new Node(key, value);
             addToHead(node);
             map.put(key, node);
         } else {
@@ -95,7 +95,7 @@ public class T55_146_LRUCache {
             this.val = val;
         }
 
-        public Node(int key ,int val, Node pre, Node next) {
+        public Node(int key, int val, Node pre, Node next) {
             this.key = key;
             this.val = val;
             this.pre = pre;
@@ -116,3 +116,90 @@ public class T55_146_LRUCache {
         System.out.println(lRUCache.get(4));    // 返回 4
     }
 }
+
+class LRUCache {
+
+    int capacity;
+    Node head;
+    Node tail;
+    Map<Integer, Node> map;
+
+    public LRUCache(int capacity) {
+        this.capacity = capacity;
+        map = new HashMap<>();
+        head = new Node();
+        tail = new Node();
+        head.next = tail;
+        tail.pre = head;
+    }
+
+
+    public int get(int key) {
+        Node node = map.get(key);
+        if (node == null) {
+            return -1;
+        } else {
+            removeNode(node);
+            addToHead(node);
+            return node.value;
+        }
+    }
+
+
+    public void put(int key, int value) {
+        Node node = map.get(key);
+        if (node == null) {
+            if (map.size() == capacity) {
+                //需要删除末尾的
+                Node del = deleteTail();
+                map.remove(del.key);
+            }
+            Node add = new Node(key, value);
+            map.put(key, add);
+            addToHead(add);
+        } else {
+            //map中存在这个数据，只做更新
+            node.value = value;
+            removeNode(node);
+            addToHead(node);
+        }
+
+    }
+
+    private Node deleteTail() {
+        Node del = tail.pre;
+        removeNode(tail.pre);
+        return del;
+    }
+
+    private void removeNode(Node node) {
+        node.pre.next = node.next;
+        node.next.pre = node.pre;
+    }
+
+    private void addToHead(Node node) {
+        node.next = head.next;
+        head.next.pre = node;
+
+        node.pre = head;
+        head.next = node;
+    }
+
+    class Node {
+
+        int key;
+        int value;
+        Node pre;
+        Node next;
+
+        public Node() {
+        }
+
+        public Node(int key, int value) {
+            this.key = key;
+            this.value = value;
+        }
+
+
+    }
+}
diff --git a/Leecode/src/main/java/com/markilue/leecode/hot100/second/T63_206_ReverseList.java b/Leecode/src/main/java/com/markilue/leecode/hot100/second/T63_206_ReverseList.java
new file mode 100644
index 0000000..15e4463
--- /dev/null
+++ b/Leecode/src/main/java/com/markilue/leecode/hot100/second/T63_206_ReverseList.java
@@ -0,0 +1,27 @@
+package com.markilue.leecode.hot100.second;
+
+import com.markilue.leecode.listnode.ListNode;
+
+/**
+ *@BelongsProject: Leecode
+ *@BelongsPackage: com.markilue.leecode.hot100.second
+ *@Author: markilue
+ *@CreateTime: 2023-05-22  11:48
+ *@Description: TODO  力扣206  反转链表
+ *@Version: 1.0
+ */
+public class T63_206_ReverseList {
+
+    public ListNode reverseList(ListNode head) {
+        ListNode fake =new ListNode();
+        ListNode cur=head;
+        ListNode curNext;
+        while(cur!=null){
+            curNext=cur.next;
+            cur.next=fake.next;
+            fake.next=cur;
+            cur=curNext;
+        }
+        return fake.next;
+    }
+}
diff --git a/Leecode/src/main/java/com/markilue/leecode/hot100/second/T64_207_CanFinish.java b/Leecode/src/main/java/com/markilue/leecode/hot100/second/T64_207_CanFinish.java
new file mode 100644
index 0000000..68aa13f
--- /dev/null
+++ b/Leecode/src/main/java/com/markilue/leecode/hot100/second/T64_207_CanFinish.java
@@ -0,0 +1,117 @@
+package com.markilue.leecode.hot100.second;
+
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ *@BelongsProject: Leecode
+ *@BelongsPackage: com.markilue.leecode.hot100.second
+ *@Author: markilue
+ *@CreateTime: 2023-05-22  11:49
+ *@Description: TODO  力扣207  课程表
+ *@Version: 1.0
+ */
+public class T64_207_CanFinish {
+
+    @Test
+    public void test() {
+        int numCourses = 2;
+        int[][] prerequisites = {{1, 0}, {0, 1}};
+        System.out.println(canFinish(numCourses, prerequisites));
+    }
+
+
+    //其实本质上就是监测是否存在环
+    List<List<Integer>> edge;//边
+
+    //本质上就是图的深度优先搜索:检测这个图是否存在环路
+    //TODO 超出时间限制了:因为这样有很多重复的计算,一个节点作为别人的子节点时和自己就作为根节点时都计算了一次
+    public boolean canFinish(int numCourses, int[][] prerequisites) {
+        edge = new ArrayList<>();
+        for (int i = 0; i < numCourses; i++) {
+            edge.add(new ArrayList<>());
+        }
+        //使用一个list记录每个节点的子节点，使用dfs判断是否会回到父节点
+        for (int[] prerequisite : prerequisites) {
+            List<Integer> list = edge.get(prerequisite[0]);
+            list.add(prerequisite[1]);//添加子节点
+        }
+        boolean[] used = new boolean[numCourses];
+        for (int i = 0; i < edge.size(); i++) {
+            if(!used[i]){
+                if (!dfs(i, used)) {
+                    return false;
+                }
+            }
+        }
+
+        return true;
+
+    }
+
+    public boolean dfs(int start, boolean[] used) {
+        if (start >= edge.size()) {
+            return true;
+        }
+        used[start] = true;//当前节点已经遍历过
+
+        List<Integer> children = edge.get(start);
+        for (int i = 0; i < children.size(); i++) {
+            Integer cur = children.get(i);
+            if (used[cur]) {
+                return false;
+            }
+            if (!dfs(cur, used)) {
+                return false;
+            }
+            used[cur] = false;
+        }
+
+        return true;
+    }
+
+    boolean valid = true;
+
+    public boolean canFinish1(int numCourses, int[][] prerequisites) {
+        edge = new ArrayList<>();
+        for (int i = 0; i < numCourses; i++) {
+            edge.add(new ArrayList<>());
+        }
+        //使用一个list记录每个节点的子节点，使用dfs判断是否会回到父节点
+        for (int[] prerequisite : prerequisites) {
+            edge.get(prerequisite[0]).add(prerequisite[1]);//添加子节点
+        }
+
+        int[] visited = new int[numCourses];
+        for (int i = 0; i < edge.size()&&valid; i++) {
+            if (visited[i] == 0) {
+                //从来没有遍历过
+                dfs(i, visited);
+            }
+        }
+
+        return valid;
+    }
+
+    public void dfs(int start, int[] visited) {
+        visited[start] = 1;//设置为遍历过了
+        List<Integer> childern = edge.get(start);
+        for (Integer child : childern) {
+            if (visited[child] == 0) {
+                //没有遍历过继续判断他是否可以
+                dfs(child, visited);
+                //判断是否还需要遍历
+                if (!valid) {
+                    return;
+                }
+            } else if (visited[child] == 1) {
+                valid = false;//有问题,监测到环路了
+                return;
+            }
+        }
+        visited[start] = 2;//全都检查完了,没有问题
+    }
+
+}