Go: Soultion for 150-Evaluate-Reverse-Polish-Notation.go

Author: Rushi Panchariya

Diff for: go/150-Evaluate-Reverse-Polish-Notation.go

@@ -0,0 +1,32 @@
+func evalRPN(tokens []string) int {
+	var stack []int
+	var a, b int
+	for _, c := range tokens {
+		switch c {
+		case "+":
+			a, b, stack = getAndPopLastOperand(stack)
+			stack = append(stack, (a + b))
+		case "-":
+			a, b, stack = getAndPopLastOperand(stack)
+			stack = append(stack, (a - b))
+		case "*":
+			a, b, stack = getAndPopLastOperand(stack)
+			stack = append(stack, (a * b))
+		case "/":
+			a, b, stack = getAndPopLastOperand(stack)
+			stack = append(stack, (a / b))
+		default:
+			i, _ := strconv.Atoi(c)
+			stack = append(stack, i)
+		}
+	}
+	return stack[0]
+}
+
+func getAndPopLastOperand(stack []int) (int, int, []int) {
+	a := stack[len(stack)-2]
+	b := stack[len(stack)-1]
+	stack = stack[:len(stack)-2]
+
+	return a, b, stack
+}