package leetcode

type stack struct {
	array [10000]string
	index int
}

var m = map[string]string{
	"}": "{",
	")": "(",
	"]": "[",
}

func (s *stack) push(r string) bool {
	switch r {
	case "(":
		fallthrough
	case "{":
		fallthrough
	case "[":
		s.array[s.index] = r
		s.index++
	case ")":
		fallthrough
	case "}":
		fallthrough
	case "]":
		if s.index == 0 {
			return false
		}
		s.index = s.index - 1
		o := m[r]
		if o != s.array[s.index] {
			return false
		}
	}
	return true
}

func (s *stack) empty() bool {
	return s.index == 0
}

func isValid(s string) bool {
	st := &stack{}
	for i := 0; i < len(s); i++ {
		if !st.push(s[i : i+1]) {
			return false
		}
	}
	return st.empty()
}