Valid Parentheses

LeetCode 20 · View on LeetCode

Push opening brackets onto the stack. When you hit a closing bracket, pop and check if it matches. If the stack is empty at the end, the string is valid.

package main

import "fmt"

func isValid(s string) bool {
	stack := []byte{}
	pairs := map[byte]byte{')': '(', ']': '[', '}': '{'}

	for i := 0; i < len(s); i++ {
		if s[i] == '(' || s[i] == '[' || s[i] == '{' {
			stack = append(stack, s[i])
		} else {
			if len(stack) == 0 || stack[len(stack)-1] != pairs[s[i]] {
				return false
			}
			stack = stack[:len(stack)-1]
		}
	}
	return len(stack) == 0
}

func main() {
	fmt.Println(isValid("()[]{}")) // true
	fmt.Println(isValid("(]"))     // false
	fmt.Println(isValid("{[]}"))   // true
	fmt.Println(isValid("([)]"))   // false
}