From 77b31bb0caaca95080c29844098f6bbb0e7f75b1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=9E=81=E5=AE=A2=E5=AD=A6=E4=BC=9F?= <qxuewei@yeah.net>
Date: Tue, 30 Nov 2021 14:07:32 +0800
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=20150.=20=E9=80=86=E6=B3=A2?=
 =?UTF-8?q?=E5=85=B0=E8=A1=A8=E8=BE=BE=E5=BC=8F=E6=B1=82=E5=80=BC=20Swift?=
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---
 problems/0150.逆波兰表达式求值.md | 32 +++++++++++++++++++++++
 1 file changed, 32 insertions(+)

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 ef91330d..137aaf5d 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
@@ -241,6 +241,38 @@ class Solution:
 
 ```
 
+Swift：
+```Swift
+func evalRPN(_ tokens: [String]) -> Int {
+    var stack = [Int]()
+    for c in tokens {
+        let v = Int(c)
+        if let num = v {
+            // 遇到数字直接入栈
+            stack.append(num)
+        } else {
+            // 遇到运算符, 取出栈顶两元素计算, 结果压栈
+            var res: Int = 0
+            let num2 = stack.popLast()!
+            let num1 = stack.popLast()!
+            switch c {
+            case "+":
+                res = num1 + num2
+            case "-":
+                res = num1 - num2
+            case "*":
+                res = num1 * num2
+            case "/":
+                res = num1 / num2
+            default:
+                break
+            }
+            stack.append(res)
+        }
+    }
+    return stack.last!
+}
+```
 
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 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>