golang力扣leetcode 394.字符串解码

package main
import "strconv"
func decodeString(s string) string {
  if len(s) == 0 {
    return ""
  }
  stack := make([]byte, 0, len(s))
  for i := 0; i < len(s); i++ {
    by := s[i]
    switch by {
    case ']':
      cnt := make([]byte, 0, len(s))
      //pop string
      for stack[len(stack)-1] != '[' {
        cnt = append(cnt, stack[len(stack)-1])
        stack = stack[:len(stack)-1]
      }
      //pop [
      stack = stack[:len(stack)-1]
      //pop count
      count := ""
      for len(stack) != 0 && stack[len(stack)-1] >= '0' && stack[len(stack)-1] <= '9' {
        count = count + string(stack[len(stack)-1])
        stack = stack[:len(stack)-1]
      }
      //reverse count for num
      num := 0
      for i := len(count) - 1; i >= 0; i-- {
        v, _ := strconv.Atoi(string(count[i]))
        num = num*10 + v
      }
      //insert string
      for i := 0; i < num; i++ {
        for j := len(cnt) - 1; j >= 0; j-- {
          stack = append(stack, cnt[j])
        }
      }
    default:
      stack = append(stack, by)
    }
  }
  return string(stack)
}
func main() {
}