diff --git a/problems/0150.逆波兰表达式求值.md b/problems/0150.逆波兰表达式求值.md
index 8107e4e0..257bbb9a 100644
--- a/problems/0150.逆波兰表达式求值.md
+++ b/problems/0150.逆波兰表达式求值.md
@@ -89,26 +89,32 @@ C++代码如下：
 class Solution {
 public:
     int evalRPN(vector<string>& tokens) {
-        stack<int> st;
+        // 考虑到第20个样例使用int会溢出
+        // 此处使用long long来存储number
+        // 在最后用int()强行转换成int输出
+        
+        stack<long long> st; 
         for (int i = 0; i < tokens.size(); i++) {
             if (tokens[i] == "+" || tokens[i] == "-" || tokens[i] == "*" || tokens[i] == "/") {
-                int num1 = st.top();
+                long long num1 = st.top();
                 st.pop();
-                int num2 = st.top();
+                long long num2 = st.top();
                 st.pop();
                 if (tokens[i] == "+") st.push(num2 + num1);
                 if (tokens[i] == "-") st.push(num2 - num1);
                 if (tokens[i] == "*") st.push(num2 * num1);
                 if (tokens[i] == "/") st.push(num2 / num1);
             } else {
-                st.push(stoi(tokens[i]));
+                st.push(atoll(tokens[i].c_str()));
             }
         }
-        int result = st.top();
+
+        long long result = st.top();
         st.pop(); // 把栈里最后一个元素弹出（其实不弹出也没事）
-        return result;
+        return int(result);
     }
 };
+
 ```
 
 ## 题外话