Created
March 1, 2017 09:26
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package com.zola.leetcode; | |
import java.util.ArrayList; | |
import java.util.Arrays; | |
import java.util.List; | |
import java.util.Stack; | |
public class Solution20 { | |
public static void main(String[] args) { | |
// TODO Auto-generated method stub | |
String validStr = "((( { 45} )))"; | |
System.out.println(new Solution20().isValid(validStr)); | |
String invalidStr = "))4a(){}"; | |
System.out.println(new Solution20().isValid(invalidStr)); | |
} | |
public boolean isValid(String s) { | |
Stack<Character> stack = new Stack<Character>(); | |
List<Character> targets = Arrays.asList(new Character[]{'(',')','[',']','{','}'}); | |
for ( int i = 0 ; i < s.length() ; i++){ | |
Character element = s.charAt(i); | |
if (!targets.contains(element)){ | |
continue; | |
} | |
boolean isOpenCharacter = element.equals('(') || element.equals('{') || element.equals('['); | |
boolean isValidClosingParenthesis = element.equals(')') && !stack.isEmpty() && stack.peek()=='(' ; | |
boolean isValidClosingSquares = element.equals(']') && !stack.isEmpty() && stack.peek()=='[' ; | |
boolean isValidClosingBrackets = element.equals('}')&& !stack.isEmpty() && stack.peek()=='{' ; | |
if ( isOpenCharacter ){ | |
stack.push(element); | |
}else if (isValidClosingParenthesis ){ | |
stack.pop(); | |
}else if(isValidClosingSquares ){ | |
stack.pop(); | |
}else if(isValidClosingBrackets){ | |
stack.pop(); | |
}else { | |
return false; | |
} | |
} | |
return stack.isEmpty(); | |
} | |
} |
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