diff --git a/notes/Leetcode 题解 - 动态规划.md b/notes/Leetcode 题解 - 动态规划.md
index b50a12e6..e0ad50f9 100644
--- a/notes/Leetcode 题解 - 动态规划.md	
+++ b/notes/Leetcode 题解 - 动态规划.md	
@@ -807,7 +807,7 @@ sum(P) + sum(N) + sum(P) - sum(N) = target + sum(P) + sum(N)
 ```java
 public int findTargetSumWays(int[] nums, int S) {
     int sum = computeArraySum(nums);
-    if (sum < S || (sum + S) % 2 == 1) {
+    if (sum < Math.abs(S) || (sum + S) % 2 == 1) {
         return 0;
     }
     int W = (sum + S) / 2;