Leetcode||20.Valid Parentheses

20. Valid Parentheses

• Total Accepted: 149046
• Total Submissions: 471508
• Difficulty: Easy
• Contributors: Admin

Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

The brackets must close in the correct order, "()" and "()[]{}" are all valid but "(]" and "([)]" are not.

这题很有意思，大一就有了，当时是用C语言用栈写的，这次是用Java写，还是Java简单的多啊

代码如下：

public class Solution {
    public boolean isValid(String s) {
        Stack<Integer> stack = new Stack<Integer>();
        for (int i = 0; i < s.length(); i++) {
			int pos = "()[]{}".indexOf(s.substring(i, i+1));
			if (pos % 2 == 1) {
				if (stack.isEmpty() || stack.pop() != pos-1) {
					return false;
				}
			} else {
				stack.push(pos);
			}
		}
        return stack.isEmpty();
    }
}