Update 0216.组合总和III.md

problems/0216.组合总和III.md

@@ -360,28 +360,25 @@ class Solution {
 
 ```py
 class Solution:
-    def __init__(self):
-        self.res = []
-        self.sum_now = 0
-        self.path = []
+    def combinationSum3(self, k: int, n: int) -> List[List[int]]:
+        result = []  # 存放结果集
+        self.backtracking(n, k, 0, 1, [], result)
+        return result
 
-    def combinationSum3(self, k: int, n: int) -> [[int]]:
-        self.backtracking(k, n, 1)
-        return self.res
+    def backtracking(self, targetSum, k, currentSum, startIndex, path, result):
+        if currentSum > targetSum:  # 剪枝操作
+            return  # 如果path的长度等于k但currentSum不等于targetSum，则直接返回
+        if len(path) == k:
+            if currentSum == targetSum:
+                result.append(path[:])
+            return
+        for i in range(startIndex, 9 - (k - len(path)) + 2):  # 剪枝
+            currentSum += i  # 处理
+            path.append(i)  # 处理
+            self.backtracking(targetSum, k, currentSum, i + 1, path, result)  # 注意i+1调整startIndex
+            currentSum -= i  # 回溯
+            path.pop()  # 回溯
 
-    def backtracking(self, k: int, n: int, start_num: int):
-        if self.sum_now > n:  # 剪枝
-            return
-        if len(self.path) == k:  # len(path)==k时不管sum是否等于n都会返回
-            if self.sum_now == n:
-                self.res.append(self.path[:])
-            return
-        for i in range(start_num, 10 - (k - len(self.path)) + 1):
-            self.path.append(i)
-            self.sum_now += i
-            self.backtracking(k, n, i + 1)
-            self.path.pop()
-            self.sum_now -= i
 ```
 
 ## Go