代码随想录算法训练营第十一天 | 150

150. 逆波兰表达式求值

package main

import "strconv"

func evalRPN(tokens []string) int {
    stack := []int{}
    for _, token := range tokens {
        switch token {
        case "+", "-", "*", "/":
            // 弹出两个操作数
            b := stack[len(stack)-1]
            stack = stack[:len(stack)-1]
            a := stack[len(stack)-1]
            stack = stack[:len(stack)-1]
            var res int
            switch token {
            case "+":
                res = a + b
            case "-":
                res = a - b
            case "*":
                res = a * b
            case "/":
                res = a / b
            }
            stack = append(stack, res)
        default:
            num, _ := strconv.Atoi(token)
            stack = append(stack, num)
        }
    }
    return stack[0]
}