Created
February 19, 2017 12:17
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import java.util.*; | |
public class Groups{ | |
private static final List<Character> OPEN = Arrays.asList('(', '{', '['); | |
private static final List<Character> CLOSE = Arrays.asList(')', '}', ']'); | |
public static boolean groupCheck(String s){ | |
if (s == null || s.length() == 0) { | |
return true; | |
} | |
Stack<Character> stack = new Stack<>(); | |
for (int i = 0; i < s.length(); i++) { | |
char current = s.charAt(i); | |
if (isOpen(current)) { | |
stack.push(current); | |
} else { | |
if (stack.isEmpty()) { | |
return false; | |
} | |
char prev = stack.peek(); | |
if (isMatch(prev, current)) { | |
stack.pop(); | |
} | |
} | |
} | |
return stack.isEmpty(); | |
} | |
private static boolean isOpen(char c) { | |
return OPEN.contains(c); | |
} | |
private static boolean isClose(char c) { | |
return CLOSE.contains(c); | |
} | |
private static boolean isMatch(char prev, char next) { | |
return isOpen(prev) && (OPEN.indexOf(prev) == CLOSE.indexOf(next)); | |
} | |
} |
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