解题思路
将其他字符去掉之后,只剩下括号,遇见左括号入栈,右括号则弹栈,弹栈时无法匹配则返回false。
import java.util.LinkedList;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
String str = sc.nextLine();
String pattern = "[^\\[\\]\\{\\}\\(\\)]";
String strNew = str.replaceAll(pattern, "");
System.out.println(isValid(strNew));
}
public static boolean isValid(String str) {
LinkedList<Character> stack = new LinkedList<Character>();
for (int i = 0; i < str.length(); i++) {
if (str.charAt(i) == '(' || str.charAt(i) == '[' || str.charAt(i) == '{') {
stack.push(str.charAt(i));
} else if (str.charAt(i) == ')' && stack.size() > 0 && stack.peek() == '(') {
stack.pop();
} else if (str.charAt(i) == ']' && stack.size() > 0 && stack.peek() == '[') {
stack.pop();
} else if (str.charAt(i) == '}' && stack.size() > 0 && stack.peek() == '{') {
stack.pop();
} else {
return false;
}
}
return stack.isEmpty();
}
}