diff --git a/problems/0494.目标和.md b/problems/0494.目标和.md
index 8f116fae..cc8a08e3 100644
--- a/problems/0494.目标和.md
+++ b/problems/0494.目标和.md
@@ -213,6 +213,7 @@ public:
         if (abs(S) > sum) return 0; // 此时没有方案
         if ((S + sum) % 2 == 1) return 0; // 此时没有方案
         int bagSize = (S + sum) / 2;
+	if (bagsize < 0) return 0;
         vector<int> dp(bagSize + 1, 0);
         dp[0] = 1;
         for (int i = 0; i < nums.size(); i++) {