Solution.go

func isValid(s string) bool {
	stack := newStack()
    for _, str := range s {
		if str == '(' || str == '[' || str == '{' {
            stack.push(byte(str))
        } else if str == ')' {
            if stack.pop() != (byte('(')) {
				return false
			}
        } else if str == ']' {
            if stack.pop() != (byte('[')) {
				return false
			}
        } else if str == '}' {
            if stack.pop() != (byte('{')) {
				return false
			}
        }
	}
    return stack.size() == 0
}

type Stack struct {
	data []byte
	index int
}

func newStack() *Stack {
	return &Stack{
		data: make([]byte, 10),
	}
}

func (s *Stack) pop() byte {
    if s.index == 0 {
        return 0
    }
    s.index--
    r := s.data[s.index]
    return r
}

func (s *Stack) push(b byte) {
	if len(s.data) - 1 <= s.index {
		newData := make([]byte, len(s.data))
        s.data = append(s.data, newData[:]...)
	}
	s.data[s.index] = b
	s.index++
}

func (s *Stack) size() int {
    return s.index
}