package main

import "fmt"

func main() {
    ret := isValid("{[]()}")
    fmt.Println(ret)
}

func isValid(s string) bool {
    if len(s) == 0 {
        return true
    }
    str := []byte(s)
    N := len(str)
    stack := make([]byte, N)
    size := 0
    for i := 0; i < N; i++ {
        cha := str[i]
        if cha == '(' || cha == '[' || cha == '{' {
            stack[size] = twoSelectOne(cha == '(', ')', (twoSelectOne(cha == '[', ']', '}')))
            size++
        } else {
            if size == 0 {
                return false
            }
            size--
            last := stack[size]
            if cha != last {
                return false
            }
        }
    }
    return size == 0
}

func twoSelectOne(c bool, a byte, b byte) byte {
    if c {
        return a
    } else {
        return b
    }
}