diff --git a/problems/0139.单词拆分.md b/problems/0139.单词拆分.md
index 1653a81a..e04cb173 100644
--- a/problems/0139.单词拆分.md
+++ b/problems/0139.单词拆分.md
@@ -89,27 +89,26 @@ class Solution {
 private:
     bool backtracking (const string& s,
             const unordered_set<string>& wordSet,
-            vector<int>& memory,
+            vector<bool>& memory,
             int startIndex) {
         if (startIndex >= s.size()) {
             return true;
         }
         // 如果memory[startIndex]不是初始值了，直接使用memory[startIndex]的结果
-        if (memory[startIndex] != -1) return memory[startIndex];
+        if (!memory[startIndex]) return memory[startIndex];
         for (int i = startIndex; i < s.size(); i++) {
             string word = s.substr(startIndex, i - startIndex + 1);
             if (wordSet.find(word) != wordSet.end() && backtracking(s, wordSet, memory, i + 1)) {
-                memory[startIndex] = 1; // 记录以startIndex开始的子串是可以被拆分的
                 return true;
             }
         }
-        memory[startIndex] = 0; // 记录以startIndex开始的子串是不可以被拆分的
+        memory[startIndex] = false; // 记录以startIndex开始的子串是不可以被拆分的
         return false;
     }
 public:
     bool wordBreak(string s, vector<string>& wordDict) {
         unordered_set<string> wordSet(wordDict.begin(), wordDict.end());
-        vector<int> memory(s.size(), -1); // -1 表示初始化状态
+        vector<bool> memory(s.size(), 1); // -1 表示初始化状态
         return backtracking(s, wordSet, memory, 0);
     }
 };