Valid Parentheses

最新推荐文章于 2021-02-23 15:41:56 发布

最新推荐文章于 2021-02-23 15:41:56 发布 · 78 阅读

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本文提供了一个关于如何通过栈操作来验证给定字符串中的括号是否有效排列的算法实现。

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.

public class Solution {
    public boolean isValid(String s) {
        Stack<Character> stack = new Stack<Character>();
        for (int i = 0; i < s.length(); i++) {
        	char ch = s.charAt(i);
        	if (ch=='(' || ch=='{' || ch=='[') {
        		stack.push(ch);
        	}
        	if (ch==')' && (stack.empty()||stack.pop()!='(')) {
        		return false;
        	}
        	if (ch==']' && (stack.empty()||stack.pop()!='[')) {
        		return false;
        	}
        	if (ch=='}' && (stack.empty()||stack.pop()!='{')) {
        		return false;
        	}
        }
        if (!stack.empty()) {
        	return false;
        }
        return true;
    }
}