class Solution {
    int index = 0;
    public NestedInteger deserialize(String s) {
        if (s.charAt(index) == '[') {
            index++;
            NestedInteger ni = new NestedInteger();
            while (s.charAt(index) != ']') {
                ni.add(deserialize(s));
                if (s.charAt(index) == ',') {
                    index++;
                }
            }
            index++;
            return ni;
        } else {
            boolean negative = false;
            if (s.charAt(index) == '-') {
                negative = true;
                index++;
            }
            int num = 0;
            while (index < s.length() && Character.isDigit(s.charAt(index))) {
                num = num * 10 + s.charAt(index) - '0';
                index++;
            }
            if (negative) {
                num *= -1;
            }
            return new NestedInteger(num);
        }
    }
}

func deserialize(s string) *NestedInteger {
  if s[0] != '[' {
    integer, _ := strconv.Atoi(s)
    nestedInteger := &NestedInteger{}
    nestedInteger.SetInteger(integer)
    return nestedInteger
  }
  stack, integer := []*NestedInteger{}, ""
  for _, ch := range s {
    switch ch {
      case '[':
        stack = append(stack, &NestedInteger{}) // 入棧
      case ']':
        fallthrough
      case ',':
        if integer != "" {
          int, _ := strconv.Atoi(integer)
          nestedInteger := NestedInteger{}
          nestedInteger.SetInteger(int)
          stack[len(stack) - 1].Add(nestedInteger)
          integer = ""
        }
        if ch == ']' && len(stack) > 1 { // 出棧
          stack[len(stack) - 2].Add(*stack[len(stack) - 1])
          stack = stack[:len(stack) - 1]
        }
      default:
        integer += string(ch)
    }
  }
  return stack[len(stack) - 1]
}