leetcode: Add cpp impl to 0150

src/SUMMARY.md

@@ -270,6 +270,7 @@
         - [0125. 验证回文串 Valid Palindrome](leetcode/0125.valid-palindrome/index.md)
         - [0136. 只出现一次的数字 Single Number](leetcode/0136.single-number/index.md)
         - [0137. 只出现一次的数字II Single Number II](leetcode/0137.single-number-ii/index.md)
+        - [0150. 逆波兰表达式求值 Evaluate Reverse Polish Notation](leetcode/0150.evaluate-reverse-polish-notation/index.md)
         - [0153. 寻找旋转排序数组中的最小值 Find Minimum in Rotated Sorted Array](leetcode/0153.find-minimum-in-rotated-sorted-array/index.md)
         - [0154. 寻找旋转排序数组中的最小值 II Find Minimum in Rotated Sorted Array II](leetcode/0154.find-minimum-in-rotated-sorted-array-ii/index.md)
         - [0155. 最小栈 Min Stack](leetcode/0155.min-stack/index.md)

src/leetcode/0150.evaluate-reverse-polish-notation/.gitignore

@@ -0,0 +1 @@
+/main

src/leetcode/0150.evaluate-reverse-polish-notation/Makefile

@@ -0,0 +1,3 @@
+
+build: main.cpp
+	g++ -g main.cpp -o main

src/leetcode/0150.evaluate-reverse-polish-notation/index.md

@@ -1,4 +1,21 @@
+# 0150. 逆波兰表达式求值 Evaluate Reverse Polish Notation
 
-# 
+[问题描述](https://leetcode.com/problems/evaluate-reverse-polish-notation)
 
-[问题描述](../problems/)
+这个问题是解析后缀表达式, 可以用栈来完成.
+
+但要注意操作符对应的左右两侧的数值顺序.
+
+## 代码实现
+
+### Rust
+
+```rust
+{{#include src/main.rs:41:85}}
+```
+
+### C++
+
+```cpp
+{{#include main.cpp:5:}}
+```

src/leetcode/0150.evaluate-reverse-polish-notation/main.cpp

@@ -0,0 +1,62 @@
+// Copyright (c) 2024 Xu Shaohua <shaohua@biofan.org>. All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+#include <cassert>
+
+#include <stack>
+#include <string>
+#include <vector>
+
+int evalRPN(std::vector<std::string>& tokens) {
+  std::stack<int> stack;
+
+  for (const std::string& token : tokens) {
+    if (token == "+") {
+      const int num1 = stack.top();
+      stack.pop();
+      const int num2 = stack.top();
+      stack.pop();
+      const int num = num2 + num1;
+      stack.push(num);
+    } else if (token == "-") {
+      const int num1 = stack.top();
+      stack.pop();
+      const int num2 = stack.top();
+      stack.pop();
+      const int num = num2 - num1;
+      stack.push(num);
+    } else if (token == "*") {
+      const int num1 = stack.top();
+      stack.pop();
+      const int num2 = stack.top();
+      stack.pop();
+      const int num = num2 * num1;
+      stack.push(num);
+    } else if (token == "/") {
+      const int num1 = stack.top();
+      stack.pop();
+      const int num2 = stack.top();
+      stack.pop();
+      const int num = num2 / num1;
+      stack.push(num);
+    } else {
+      const int num = std::stoi(token);
+      stack.push(num);
+    }
+  }
+
+  // 栈顶的元素就是计算结果.
+  return stack.top();
+}
+
+void check_solution() {
+  std::vector<std::string> tokens = {"4","13","5","/","+"};
+  const int ret = evalRPN(tokens);
+  assert(ret == 6);
+}
+
+int main() {
+  check_solution();
+  return 0;
+}

src/leetcode/tags/stack/index.md

@@ -15,8 +15,9 @@ TODO:
 ## 中等
 
 1. [0071. 简化路径 Simplify Path](../../0071.simplify-path/index.md)
-2. [0155. 最小栈 Min Stack](../../0155.min-stack/index.md)
-3. [0394. 字符串解码 Decode String](../../0394.decode-string/index.md)
+2. [0150. 逆波兰表达式求值 Evaluate Reverse Polish Notation](../../0150.evaluate-reverse-polish-notation/index.md)
+3. [0155. 最小栈 Min Stack](../../0155.min-stack/index.md)
+4. [0394. 字符串解码 Decode String](../../0394.decode-string/index.md)
 
 TODO: