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valid parentheses

admin 11月 11, 2020 0

Problem:

Given a string, valid if this is a valid parentheses.

分析

经典的栈题目。遇见左括号，推入栈；遇见右括号，进行匹配。最后返回栈的大小是否为0.

public class  {
    public boolean isValid(String s) {
        if (s.length() == 0) {
            return true;
        }
        Deque<Character> deque = new ArrayDeque<>();
        for (int i = 0; i < s.length(); i++) {
            char cur = s.charAt(i);
            if (deque.isEmpty()) {
                deque.push(cur);
            } else if (cur - deque.peek() == 1 || cur - deque.peek() == 2) {
                deque.pop();
            } else {
                deque.push(cur);
            }
        }
        return deque.isEmpty();
    }
}