Update qqchangE_problem.md

src/qqchangE_problem.md

 ```python
 def canPartition(nums):
     def dfs(nums, target, num):
+        n = len(nums)
         for i in range(n):
             B = nums[:i] + nums[i + 1:]
             if num + nums[i] == target:
@@ -12,17 +13,32 @@ def canPartition(nums):
                 return False
         return False
 
-    n, total = len(nums), sum(nums)
-    if total % 2 != 0: return False
+    total = sum(nums)
+
+    if total % 2 != 0:
+        return False
+
     target = total // 2
+
     nums.sort(reverse=True)  # 逆序排序，先从大的开始判断，速度会更快
+
     res = dfs(nums, target, 0)
     return res
 
 
 print(canPartition([3, 3, 3, 4, 5]))
+print(canPartition([1,1,2]))
+print(canPartition([1,2,3,4]))
+print(canPartition([2,3]))
+print(canPartition([2,2,2,2,6]))
+print(canPartition([1,2,2,2,2,7]))
 
 
 output:
 True
+True
+True
+False
+False
+True
 ```