g0001_0100.s0020_valid_parentheses.Solution.kt Maven / Gradle / Ivy

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package g0001_0100.s0020_valid_parentheses

// #Easy #Top_100_Liked_Questions #Top_Interview_Questions #String #Stack
// #Data_Structure_I_Day_9_Stack_Queue #Udemy_Strings
// #2022_10_06_Time_226_ms_(72.53%)_Space_34.1_MB_(76.91%)

import java.util.Stack

class Solution {
    fun isValid(s: String): Boolean {
        val stack = Stack()
        for (element in s) {
            val c = element
            if (c == '(' || c == '[' || c == '{') {
                stack.push(c)
            } else if (c == ')' && !stack.isEmpty() && stack.peek() == '(') {
                stack.pop()
            } else if (c == '}' && !stack.isEmpty() && stack.peek() == '{') {
                stack.pop()
            } else if (c == ']' && !stack.isEmpty() && stack.peek() == '[') {
                stack.pop()
            } else {
                return false
            }
        }
        return stack.isEmpty()
    }
}