add sol

leetcode/150.EvaluateReversePolishNotation/evaluateReversePolishNotation.go

@@ -0,0 +1,51 @@
+// https://leetcode.com/problems/evaluate-reverse-polish-notation
+
+package main
+
+import (
+	"fmt"
+	"strconv"
+)
+
+func evalRPN(tokens []string) int {
+	var stack []int
+	stackSize := 0
+
+	for _, token := range tokens {
+		if token == "+" || token == "-" || token == "*" || token == "/" {
+			var res int
+			op1, op2 := stack[stackSize-2], stack[stackSize-1]
+
+			switch token {
+			case "+":
+				res = op1 + op2
+			case "-":
+				res = op1 - op2
+			case "*":
+				res = op1 * op2
+			case "/":
+				res = op1 / op2
+			}
+
+			stack = stack[0 : stackSize-2]
+			stack = append(stack, res)
+
+			stackSize--
+
+			continue
+		}
+
+		converted, _ := strconv.Atoi(token)
+
+		stack = append(stack, converted)
+		stackSize++
+	}
+
+	return stack[0]
+}
+
+func main() {
+	tokens := []string{"2", "1", "+", "3", "*"}
+
+	fmt.Println(evalRPN(tokens))
+}