diff --git a/src/leo/class04_07/CoverMax.java b/src/leo/class04_07/CoverMax.java
index 5883875..d87d559 100644
--- a/src/leo/class04_07/CoverMax.java
+++ b/src/leo/class04_07/CoverMax.java
@@ -3,6 +3,7 @@ package leo.class04_07;
 import java.util.Arrays;
 import java.util.Comparator;
 import java.util.PriorityQueue;
+import java.util.Stack;
 
 /**
  * @author Leo
@@ -153,6 +154,49 @@ class CoverMax2 {
 
 }
 
+class CoverMax3{
+
+    static class Line{
+        private int start;
+        private int end;
+
+        public Line(int s, int end) {
+            this.start = s;
+            this.end = end;
+        }
+    }
+
+    static class  StartComparator implements Comparator<Line>{
+
+        @Override
+        public int compare(Line o1, Line o2) {
+            return o1.start - o2.start;
+        }
+    }
+
+    public static int maxCover(int[][] arr) {
+        if (arr.length == 0 || arr == null) {
+
+            return 0;
+        }
+        Line[] lines = new Line[arr.length];
+        for (int i = 0; i < arr.length; i++) {
+            lines[i] = new Line(arr[i][0], arr[i][1]);
+        }
+        Arrays.sort(lines, new StartComparator());
+        PriorityQueue<Integer> queue = new PriorityQueue<>();
+        int max = 0;
+        for (int i = 0; i < lines.length; i++) {
+            if (!queue.isEmpty() && queue.peek() <= lines[i].start) {
+                queue.poll();
+            }
+            queue.add(lines[i].end);
+            max = Math.max(max, queue.size());
+        }
+        return max;
+    }
+}
+
 class CoverMaxForTest{
 
     public static int maxCover(int[][] arr) {
@@ -189,7 +233,7 @@ class CoverMaxMain {
 
         for (int i = 0; i < testTime; i++) {
             int[][] lines = generateLines(sizeMax, L, R);
-            int max = CoverMax2.maxCover(lines);
+            int max = CoverMax3.maxCover(lines);
             int maxForTest = CoverMaxForTest.maxCover(lines);
             if (max != maxForTest) {
                 System.out.println("max : " + max + " maxForTest : " + maxForTest);
diff --git a/src/leo/class05_08/CountSort.java b/src/leo/class05_08/CountSort.java
new file mode 100644
index 0000000..45be747
--- /dev/null
+++ b/src/leo/class05_08/CountSort.java
@@ -0,0 +1,78 @@
+package leo.class05_08;
+
+import leo.util.ArrayUtil;
+import sun.jvm.hotspot.oops.BranchData;
+
+import java.util.Arrays;
+
+/**
+ * @author Leo
+ * @ClassName CountSort
+ * @DATE 2020/12/2 2:03 下午
+ * @Description 计数排序(桶排序)
+ */
+public class CountSort {
+
+
+    public static void countSort(int[] arr) {
+        if (arr.length < 2 || arr == null) {
+            return;
+        }
+        int max = Integer.MIN_VALUE;
+        for (int i = 0; i < arr.length; i++) {
+            max = Math.max(max, arr[i]);
+        }
+        int[] bucket = new int[max + 1];
+        for (int i = 0; i < arr.length; i++) {
+            bucket[arr[i]]++;
+        }
+        int i = 0;
+        for (int j = 0; j < bucket.length; j++) {
+            while (bucket[j]-- > 0) {
+                arr[i++] = j;
+            }
+        }
+    }
+
+
+
+
+
+    public static void main(String[] args){
+        int maxSize = 100;
+        int range = 100;
+        int testTime = 10000;
+        System.out.println("start!");
+
+        for (int i = 0; i < testTime; i++) {
+            int[] arr = randomArray(maxSize, range);
+            int[] copyArray = copyArray(arr);
+            countSort(arr);
+            Arrays.sort(copyArray);
+            if (!ArrayUtil.isEqual(arr, copyArray)) {
+                ArrayUtil.printArr(arr, "arr");
+                ArrayUtil.printArr(copyArray, "copyArray");
+                System.out.println("fuck!");
+                break;
+            }
+        }
+        System.out.println("end!");
+
+    }
+
+    public static int[] randomArray(int maxSize, int range) {
+        int[] arr = new int[(int) (maxSize * Math.random() + 1)];
+        for (int i = 0; i < arr.length; i++) {
+            arr[i] = (int) (range * Math.random()) + 1;
+        }
+        return arr;
+    }
+
+    public static int[] copyArray(int[] arr) {
+        int[] copyArr = new int[arr.length];
+        for (int i = 0; i < arr.length; i++) {
+            copyArr[i] = arr[i];
+        }
+        return copyArr;
+    }
+}
diff --git a/src/leo/class05_08/RadixSort.java b/src/leo/class05_08/RadixSort.java
new file mode 100644
index 0000000..a84d7e8
--- /dev/null
+++ b/src/leo/class05_08/RadixSort.java
@@ -0,0 +1,108 @@
+package leo.class05_08;
+
+import leo.util.ArrayUtil;
+
+import java.util.Arrays;
+
+/**
+ * @author Leo
+ * @ClassName RadixSort
+ * @DATE 2020/12/2 3:55 下午
+ * @Description 基数排序 要求必须是正整数
+ * O(n*log10^max)
+ * O(n)
+ */
+public class RadixSort {
+
+    public static void radixSort(int[] arr) {
+        if (arr.length < 2 || arr == null) {
+            return;
+        }
+        radixSort(arr, 0, arr.length - 1);
+    }
+
+    private static void radixSort(int[] arr, int l, int r) {
+        if (l >= r) {
+            return;
+        }
+        int i, j = 0;
+        int bits = maxBits(arr, l, r);
+        final int radix  = 10;
+        int[] help = new int[r - l + 1];
+        for (int b = 1; b <= bits; b++) {
+            int[] count = new int[radix];
+            for (i = l; i <= r; i++) {
+                j = getRemainder(arr[i], b);
+                count[j]++;
+            }
+            for (i = 1; i < count.length; i++) {
+                count[i] = count[i] + count[i - 1];
+            }
+            for (i = r; i >= l; i--) {
+                j = getRemainder(arr[i], b);
+                count[j]--;
+                help[count[j]] = arr[i];
+            }
+            for (i = 0; i <= r; i++) {
+                arr[i + l] = help[i];
+            }
+        }
+    }
+
+    private static int maxBits(int[] arr, int l, int r) {
+        int res = 0;
+        int max = Integer.MIN_VALUE;
+        for (int i = l; i <= r; i++) {
+            max = Math.max(max, arr[i]);
+        }
+        while (max != 0) {
+            max /= 10;
+            res++;
+        }
+        return res;
+    }
+
+    private static int getRemainder(int num, int b) {
+        return ((num / (int) Math.pow(10, b - 1)) % 10);
+    }
+
+}
+
+class RadixSortMain {
+
+    public static void main(String[] args){
+        int testTime = 1000;
+        int range = 1000;
+        int maxSize  = 40;
+        System.out.println("start");
+
+        for (int i = 0; i < testTime; i++) {
+            int[] arr = randomArray(maxSize, range);
+            int[] copyArray = copyArray(arr);
+            Arrays.sort(copyArray);
+            RadixSort.radixSort(arr);
+            if (!ArrayUtil.isEqual(arr, copyArray)) {
+                System.out.println("fuck!");
+            }
+        }
+        System.out.println("end");
+
+    }
+
+    public static int[] randomArray(int maxSize, int range) {
+        int[] arr = new int[(int) (maxSize * Math.random()) + 1];
+        for (int i = 0; i < arr.length; i++) {
+            arr[i] = (int) (range * Math.random()) + 1;
+        }
+        return arr;
+    }
+
+    public static int[] copyArray(int[] arr) {
+        int[] copyArr = new int[arr.length];
+        for (int i = 0; i < copyArr.length; i++) {
+            copyArr[i] = arr[i];
+        }
+        return copyArr;
+    }
+
+}
diff --git a/src/leo/class05_08/TrieTree.java b/src/leo/class05_08/TrieTree.java
index 839777e..b9a1d77 100644
--- a/src/leo/class05_08/TrieTree.java
+++ b/src/leo/class05_08/TrieTree.java
@@ -1,5 +1,7 @@
 package leo.class05_08;
 
+import java.util.HashMap;
+
 /**
  * @author Leo
  * @ClassName TrieTree
@@ -103,3 +105,117 @@ class TrieTree {
     }
 
 }
+
+class TrieTree_Test{
+    private HashMap<String,Integer> map;
+    public TrieTree_Test(){
+        this.map = new HashMap<>();
+    }
+
+    public void insert(String word) {
+        if (word.trim().length() == 0 || word == null) {
+            return;
+        }
+        if (map.containsKey(word)) {
+            map.put(word, map.get(word) + 1);
+        }else{
+            map.put(word, 1);
+        }
+    }
+
+    public void delete(String word) {
+        if (this.search(word) == 0) {
+            return;
+        }
+        if (this.map.get(word) == 1) {
+            map.remove(word);
+        }else{
+            this.map.put(word, this.map.get(word) - 1);
+        }
+    }
+
+    public int search(String word) {
+        if (word.trim().length() == 0 || word == null) {
+            return 0;
+        }
+        if (map.containsKey(word)) {
+            return map.get(word);
+        }
+        return 0;
+    }
+
+    public int prefixNumber(String word) {
+        if (word.trim().length() == 0 || word == null) {
+            return 0;
+        }
+        int count = 0;
+        for (String str : this.map.keySet()) {
+            if (str.startsWith(word)) {
+                count += this.map.get(str);
+            }
+        }
+        return count;
+    }
+}
+
+class TrieTree_Main {
+    public static void main(String[] args){
+        int strArrayLen = 100;
+        int strLen = 50;
+        int testTime = 10000;
+        System.out.println("start");
+        for (int i = 0; i < testTime; i++) {
+            TrieTree trieTree = new TrieTree();
+            TrieTree_Test test = new TrieTree_Test();
+            String[] strings = generateRandomString(strArrayLen, strLen);
+            for (int j = 0; j < strings.length; j++) {
+                int random = (int) Math.random();
+
+                if (random < 0.25) {
+                    trieTree.insert(strings[j]);
+                    test.insert(strings[j]);
+                }else if (random<0.5){
+                    trieTree.delete(strings[j]);
+                    test.delete(strings[j]);
+                }else if(random<0.75){
+                    int mapCount = trieTree.search(strings[j]);
+                    int testCount = test.search(strings[j]);
+                    if (mapCount != testCount) {
+                        System.out.println("mapCount : " + mapCount + " testCount : " + testCount);
+                        System.out.println("count fuck!");
+                        break;
+                    }
+                }else{
+                    int mapPreCount = trieTree.prefixNumber(strings[j]);
+                    int testPreCount = test.prefixNumber(strings[j]);
+                    if (mapPreCount != testPreCount) {
+                        System.out.println("mapPreCount : " + mapPreCount + " testPreCount : " + testPreCount);
+                        System.out.println("pre count fuck!");
+                        break;
+                    }
+                }
+            }
+        }
+        System.out.println("end");
+
+    }
+
+
+    public static String[] generateRandomString(int strArrayLen, int strLen) {
+        String[] strArray = new String[(int) (strArrayLen * Math.random() + 1)];
+
+        for (int i = 0; i < strArray.length; i++) {
+            strArray[i] = generateRandomString(strLen);
+        }
+        return strArray;
+    }
+
+    private static String generateRandomString(int strLen) {
+        char[] chars = new char[(int) (Math.random() * strLen + 1)];
+        for (int i = 0; i < chars.length; i++) {
+            int value = (int) (Math.random() * 6);
+            chars[i] = (char) (97 + value);
+        }
+        return String.valueOf(chars);
+    }
+}
diff --git a/src/leo/class05_08/TrieTree_Map.java b/src/leo/class05_08/TrieTree_Map.java
new file mode 100644
index 0000000..ea5f89c
--- /dev/null
+++ b/src/leo/class05_08/TrieTree_Map.java
@@ -0,0 +1,222 @@
+package leo.class05_08;
+
+import java.util.HashMap;
+
+/**
+ * @author Leo
+ * @ClassName TrieTree_Map
+ * @DATE 2020/12/2 10:33 上午
+ * @Description next 用map实现
+ */
+public class TrieTree_Map {
+
+    private class Node {
+        private int pass;
+        private int end;
+        private HashMap<Integer,Node> next;
+
+        public Node() {
+            this.pass = 0;
+            this.end = 0;
+            this.next = new HashMap<>();
+        }
+
+    }
+
+    private Node root;
+
+    public TrieTree_Map() {
+        this.root = new Node();
+    }
+
+    public void insert(String word) {
+        if (word == null || "".equals(word.trim())) {
+            return;
+        }
+        Node node = this.root;
+        root.pass++;
+        int path;
+        char[] chars = word.toCharArray();
+
+        for (int i = 0; i < chars.length; i++) {
+            path = chars[i];
+            if (node.next.get(path) == null) {
+                node.next.put(path, new Node());
+            }
+            node = node.next.get(path);
+            node.pass++;
+        }
+        node.end++;
+
+    }
+
+    public void delete(String word) {
+        if (search(word) == 0) {
+            return;
+        }
+        Node node = this.root;
+        node.pass--;
+        int path;
+        char[] chars = word.toCharArray();
+        for (int i = 0; i < chars.length; i++) {
+            path = chars[i];
+            if (--node.next.get(path).pass == 0) {
+                node.next.remove(path);
+                return;
+            }
+            node = node.next.get(path);
+        }
+        node.end--;
+
+    }
+
+    public int search(String word) {
+        if (word == null || "".equals(word.trim())) {
+            return 0;
+        }
+        Node node = this.root;
+        int path;
+        char[] chars = word.toCharArray();
+        for (int i = 0; i < chars.length; i++) {
+            path = chars[i];
+            if (node.next.get(path) == null) {
+                return 0;
+            }
+            node = node.next.get(path);
+        }
+        return node.end;
+    }
+
+    public int prefixNumber(String word) {
+        if (word == null || "".equals(word.trim())) {
+            return 0;
+        }
+        Node node = this.root;
+        char[] chars = word.toCharArray();
+        int path;
+        for (int i = 0; i < chars.length; i++) {
+            path = chars[i];
+            if (node.next.get(path) == null) {
+                return 0;
+            }
+            node = node.next.get(path);
+        }
+        return node.pass;
+    }
+
+}
+class TrieTree_Map_Test {
+    private HashMap<String,Integer> map;
+    public TrieTree_Map_Test(){
+        this.map = new HashMap<>();
+    }
+
+    public void insert(String word) {
+        if (word.trim().length() == 0 || word == null) {
+            return;
+        }
+        if (map.containsKey(word)) {
+            map.put(word, map.get(word) + 1);
+        }else{
+            map.put(word, 1);
+        }
+    }
+
+    public void delete(String word) {
+        if (this.search(word) == 0) {
+            return;
+        }
+        if (this.map.get(word) == 1) {
+            map.remove(word);
+        }else{
+            this.map.put(word, this.map.get(word) - 1);
+        }
+    }
+
+    public int search(String word) {
+        if (word.trim().length() == 0 || word == null) {
+            return 0;
+        }
+        if (map.containsKey(word)) {
+            return map.get(word);
+        }
+        return 0;
+    }
+
+    public int prefixNumber(String word) {
+        if (word.trim().length() == 0 || word == null) {
+            return 0;
+        }
+        int count = 0;
+        for (String str : this.map.keySet()) {
+            if (str.startsWith(word)) {
+                count += this.map.get(str);
+            }
+        }
+        return count;
+    }
+}
+
+class TrieTree_MapMain{
+
+    public static void main(String[] args){
+        int strArrayLen = 100;
+        int strLen = 50;
+        int testTime = 10000;
+        System.out.println("start");
+        for (int i = 0; i < testTime; i++) {
+            TrieTree_Map trieTree_map = new TrieTree_Map();
+            TrieTree_Map_Test test = new TrieTree_Map_Test();
+            String[] strings = generateRandomString(strArrayLen, strLen);
+            for (int j = 0; j < strings.length; j++) {
+                int random = (int) Math.random();
+
+                if (random < 0.25) {
+                    trieTree_map.insert(strings[j]);
+                    test.insert(strings[j]);
+                }else if (random<0.5){
+                    trieTree_map.delete(strings[j]);
+                    test.delete(strings[j]);
+                }else if(random<0.75){
+                    int mapCount = trieTree_map.search(strings[j]);
+                    int testCount = test.search(strings[j]);
+                    if (mapCount != testCount) {
+                        System.out.println("mapCount : " + mapCount + " testCount : " + testCount);
+                        System.out.println("count fuck!");
+                        break;
+                    }
+                }else{
+                    int mapPreCount = trieTree_map.prefixNumber(strings[j]);
+                    int testPreCount = test.prefixNumber(strings[j]);
+                    if (mapPreCount != testPreCount) {
+                        System.out.println("mapPreCount : " + mapPreCount + " testPreCount : " + testPreCount);
+                        System.out.println("pre count fuck!");
+                        break;
+                    }
+                }
+            }
+        }
+        System.out.println("end");
+
+    }
+
+
+    public static String[] generateRandomString(int strArrayLen, int strLen) {
+        String[] strArray = new String[(int) (strArrayLen * Math.random() + 1)];
+
+        for (int i = 0; i < strArray.length; i++) {
+            strArray[i] = generateRandomString(strLen);
+        }
+        return strArray;
+    }
+
+    private static String generateRandomString(int strLen) {
+        char[] chars = new char[(int) (Math.random() * strLen + 1)];
+        for (int i = 0; i < chars.length; i++) {
+            int value = (int) (Math.random() * 6);
+            chars[i] = (char) (97 + value);
+        }
+        return String.valueOf(chars);
+    }
+
+}