diff --git a/problems/0139.单词拆分.md b/problems/0139.单词拆分.md
index 7ff13f72..5b38a7a5 100644
--- a/problems/0139.单词拆分.md
+++ b/problems/0139.单词拆分.md
@@ -234,11 +234,13 @@ Java：
 ```java
 class Solution {
     public boolean wordBreak(String s, List<String> wordDict) {
+        HashSet<String> set = new HashSet<>(wordDict);
         boolean[] valid = new boolean[s.length() + 1];
         valid[0] = true;
+
         for (int i = 1; i <= s.length(); i++) {
-            for (int j = 0; j < i; j++) {
-                if (wordDict.contains(s.substring(j,i)) && valid[j]) {
+            for (int j = 0; j < i && !valid[i]; j++) {
+                if (set.contains(s.substring(j, i)) && valid[j]) {
                     valid[i] = true;
                 }
             }