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Solution.java
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47 lines (39 loc) · 1.17 KB
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import java.io.*;
import java.math.*;
import java.text.*;
import java.util.*;
import java.util.regex.*;
public class Solution {
private static final Map<Character, Character> validChars = populateValidChars();
private static Map<Character, Character> populateValidChars() {
Map<Character, Character> map = new HashMap<Character, Character>();
map.put('[', ']');
map.put('{', '}');
map.put('(', ')');
return map;
}
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
while (sc.hasNext()) {
String str = sc.next();
System.out.println(valid(str));
}
}
public static boolean valid(String str) {
Stack<Character> stack = new Stack<Character>();
for (int i = 0; i < str.length(); i++) {
char c = str.charAt(i);
if (validChars.containsKey(c)) { // opening paren
stack.push(c);
} else if (validChars.containsValue(c) && !stack.empty()) { // closing paren
char closingParen = validChars.get(stack.pop());
if (c != closingParen) {
return false;
}
} else { // invalid character
return false;
}
}
return stack.empty();
}
}