From 5efb10740ed78aa75dfb89f81ab1db5be04f7b3d Mon Sep 17 00:00:00 2001
From: Hnuczc <3260189532@qq.com>
Date: Wed, 5 Jan 2022 19:08:48 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BC=98=E5=8C=96=E5=AD=97=E7=AC=A6=E4=B8=B2?=
 =?UTF-8?q?=E5=88=A4=E6=96=AD=E9=80=BB=E8=BE=91?=
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---
 problems/0150.逆波兰表达式求值.md | 39 ++++++++---------------
 1 file changed, 13 insertions(+), 26 deletions(-)

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 7f7b2f4c..f44703f1 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
@@ -133,39 +133,26 @@ public:
 java:
 
 ```Java
-public class EvalRPN {
-
+class Solution {
     public int evalRPN(String[] tokens) {
         Deque<Integer> stack = new LinkedList();
-        for (String token : tokens) {
-            char c = token.charAt(0);
-            if (!isOpe(token)) {
-                stack.addFirst(stoi(token));
-            } else if (c == '+') {
-                stack.push(stack.pop() + stack.pop());
-            } else if (c == '-') {
-                stack.push(- stack.pop() + stack.pop());
-            } else if (c == '*') {
-                stack.push( stack.pop() * stack.pop());
+        for (int i = 0; i < tokens.length; ++i) {
+            if ("+".equals(tokens[i])) {        // leetcode 内置jdk的问题，不能使用==判断字符串是否相等
+                stack.push(stack.pop() + stack.pop());      // 注意 - 和/ 需要特殊处理
+            } else if ("-".equals(tokens[i])) {
+                stack.push(-stack.pop() + stack.pop());
+            } else if ("*".equals(tokens[i])) {
+                stack.push(stack.pop() * stack.pop());
+            } else if ("/".equals(tokens[i])) {
+                int temp1 = stack.pop();
+                int temp2 = stack.pop();
+                stack.push(temp2 / temp1);
             } else {
-                int num1 = stack.pop();
-                int num2 = stack.pop();
-                stack.push( num2/num1);
+                stack.push(Integer.valueOf(tokens[i]));
             }
         }
         return stack.pop();
     }
-    private boolean isOpe(String s) {
-        return s.length() == 1 && s.charAt(0) <'0' || s.charAt(0) >'9';
-    }
-    private int stoi(String s) {
-        return Integer.valueOf(s);
-    }
-
-    public static void main(String[] args) {
-        new EvalRPN().evalRPN(new String[] {"10","6","9","3","+","-11","*","/","*","17","+","5","+"});
-    }
-
 }
 ```