diff --git a/problems/0039.组合总和.md b/problems/0039.组合总和.md
index e78f2e2d..0f8fe4f6 100644
--- a/problems/0039.组合总和.md
+++ b/problems/0039.组合总和.md
@@ -455,7 +455,6 @@ func combinationSum(_ candidates: [Int], _ target: Int) -> [[Int]] {
     var path = [Int]()
     func backtracking(sum: Int, startIndex: Int) {
         // 终止条件
-        if sum > target { return }
         if sum == target {
             result.append(path)
             return
@@ -464,8 +463,11 @@ func combinationSum(_ candidates: [Int], _ target: Int) -> [[Int]] {
         let end = candidates.count
         guard startIndex < end else { return }
         for i in startIndex ..< end {
+            let sum = sum + candidates[i] // 使用局部变量隐藏回溯
+            if sum > target { continue } // 剪枝
+
             path.append(candidates[i]) // 处理
-            backtracking(sum: sum + candidates[i], startIndex: i) // sum这里用新变量完成回溯，i不用+1以重复访问
+            backtracking(sum: sum, startIndex: i) // i不用+1以重复访问
             path.removeLast() // 回溯
         }
     }