diff --git a/src/main/java/com/cool/hot100/substring/Num79.java b/src/main/java/com/cool/hot100/substring/Num79.java
index f07d7ac..0288198 100644
--- a/src/main/java/com/cool/hot100/substring/Num79.java
+++ b/src/main/java/com/cool/hot100/substring/Num79.java
@@ -1,5 +1,7 @@
 package com.cool.hot100.substring;
 
+import org.junit.Test;
+
 import java.util.*;
 
 /**
@@ -9,41 +11,61 @@ import java.util.*;
  * @Date: 2024/09/06/13:57
  * DayNumber 1
  * Hard 3
- * Level ?
+ * Level 6
  */
 public class Num79 {
 
     public String minWindow(String s, String t) {
-        if(s.length()<t.length()){
+        if (s.length() < t.length()) {
             return "";
         }
-        int minLeft=Integer.MIN_VALUE;
-        int minRight=Integer.MAX_VALUE;
-        int left=0;
-        int right=0;
-        char[] charArray=s.toCharArray();
-        int index=0;
-        Map<Character,Integer> tMap=new HashMap<>();
-        Map<Character,Integer> sMap=new HashMap<>();
-        for(int i=0;i<t.length();i++){
-            tMap.put(t.charAt(i),tMap.getOrDefault(i,0)+1);
+        int minLeft = 0;
+        int minRight = Integer.MAX_VALUE;
+        int left = 0;
+        int right = 0;
+        char[] charArray = s.toCharArray();
+        Map<Character, Integer> tMap = new HashMap<>();
+        Map<Character, Integer> sMap = new HashMap<>();
+        for (int i = 0; i < t.length(); i++) {
+            tMap.put(t.charAt(i), tMap.getOrDefault(t.charAt(i), 0) + 1);
         }
-        for(int i=0;i<charArray.length;i++){
-            if(tMap.containsKey(charArray[i])){
-                sMap.put(charArray[i],sMap.get(charArray[i])+1);
-                if(tMap.get(charArray[i])>sMap.get(charArray[i])){
-                    right++;
-                }else{
-                    while (sMap.get(charArray[left])>tMap.get(charArray[left])){
-                        sMap.put(charArray[left],sMap.get(charArray[left])-1);
+        for (int i = 0; i < charArray.length; i++) {
+            if (tMap.containsKey(charArray[i])) {
+                sMap.put(charArray[i], sMap.getOrDefault(charArray[i], 0) + 1);
+                if (tMap.get(charArray[i]) <= sMap.get(charArray[i]) && check(sMap, tMap)) {
+                    while (!tMap.containsKey(charArray[left]) || sMap.getOrDefault(charArray[left], Integer.MAX_VALUE) > tMap.get(charArray[left])) {
+                        if (tMap.containsKey(charArray[left])) {
+                            sMap.put(charArray[left], sMap.get(charArray[left]) - 1);
+                        }
+                        left++;
+                    }
+                    if (right - left < minRight - minLeft) {
+                        minLeft = left;
+                        minRight = right + 1;
                     }
-                    left++;
                 }
             }
             right++;
         }
-        return s.substring(left,right);
+        if (minRight == Integer.MAX_VALUE) {
+            minLeft = left;
+            minRight = 0;
+        }
+        return s.substring(minLeft, minRight);
     }
 
+    private boolean check(Map<Character, Integer> sMap, Map<Character, Integer> tMap) {
+        for (Map.Entry<Character, Integer> next : tMap.entrySet()) {
+            if (!sMap.containsKey(next.getKey()) || sMap.get(next.getKey()) < next.getValue()) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    @Test
+    public void test() {
+        System.out.println(minWindow("aa", "aa"));
+    }
 
 }