150. Evaluate Reverse Polish Notation

150. Evaluate Reverse Polish Notation/Solution.cs

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+namespace _150._Evaluate_Reverse_Polish_Notation;
+
+public class Solution
+{
+    public int EvalRPN(string[] tokens)
+    {
+        var stack = new Stack<int>(tokens.Length);
+        foreach (var token in tokens)
+        {
+            if (int.TryParse(token, out var number))
+                stack.Push(number);
+            else
+            {
+                int right = stack.Pop();
+                int left = stack.Pop();
+                char op = token[0];
+                stack.Push(Calc(op, left, right));
+            }
+        }
+        return stack.Pop();
+    }
+
+    private int Calc(char op, int left, int right) => op switch
+    {
+        '+' => left + right,
+        '-' => left - right,
+        '*' => left * right,
+        '/' => left / right,
+        _ => throw new ArgumentOutOfRangeException()
+    };
+}