[数据结构与算法]golang力扣leetcode 150.逆波兰表达式求值

150.逆波兰表达式求值

150.逆波兰表达式求值

题解

逆波兰表达式是一种后缀表达式，遇到运算符就弹出两个进行运算即可，大水题

代码

package main

import "strconv"

func evalRPN(tokens []string) int {
	if len(tokens) == 0 {
		return 0
	}
	stack := make([]int, 0, len(tokens))
	for i := 0; i < len(tokens); i++ {
		val := tokens[i]
		switch val {
		case "+", "-", "*", "/":
			a2 := stack[len(stack)-1]
			stack = stack[:len(stack)-1]
			a1 := stack[len(stack)-1]
			stack = stack[:len(stack)-1]
			result := 0
			switch val {
			case "+":
				result = a1 + a2
			case "-":
				result = a1 - a2
			case "*":
				result = a1 * a2
			case "/":
				result = a1 / a2
			}
			stack = append(stack, result)
		default:
			v, _ := strconv.Atoi(val)
			stack = append(stack, v)
		}
	}
	return stack[0]
}
func main() {

}