Leet Code Stack Problem 栈问题合集
2017-02-07 23:10
351 查看
总结
栈问题通常和对称联系起来,一个出现,必须和另一个出现才合法,例如,出现“(”,就要出现“)”才合法,当遇到对称的问题时,可以考虑是不是栈问题1. Leet Code Oj 20. Valid Parentheses
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.
给定一个只包含字符’(’,’)’,’{‘,’}’,’[‘和’]’的字符串,确定输入字符串是否有效。
括号必须以正确的顺序关闭,“()”和“()[] {}”都有效,但“(]”和“([]]”不是。
代码:
public class Solution { public boolean isValid(String s) { Stack<Integer> stack = new Stack<Integer>(); String rule = "()[]{}"; for(int i=0; i<s.length(); i++){ int index = rule.indexOf(s.substring(i, i+1)); if(index % 2 == 1){ if(stack.isEmpty() || stack.pop() != index-1){ return false; } }else{ stack.push(index); } } return stack.isEmpty(); } }
这里的思路是:
“(”必须和“)”对应,因此定义一个rule = “(){}[]”,可见左边的下标是偶数,右边的下标是基数
相关文章推荐
- Google Code Jam 2011 Qualification Round 资格赛 Problem A. Closing the Loop 问题A.关闭的环
- LeeCode Subsets 子集问题解答分析
- 【随】Unable to evaluate expression because the code is optimized or a native frame is on top of the call stack 问题解决。
- 1/20集训一 STL D. (stack 火车进站问题) Train Problem I
- LeeCode problem 1. Two Sum
- CODE JAM APAC 2015 round B: Problem A. Password Attacker(小球放进盒子的计数问题)
- Leetcode Linked List Problem 链表问题合集
- Codevs 数字三角形 问题合集
- Code Vs-problem-1012 最大公约数和最小公倍数问题
- Google Code Jam 2011 Qualification Round 资格赛 Problem B. Investing at the Market 问题B.市场投资
- 解决:The virtual machine was unable to remove all stack frame runnning old code from the call stack.问题
- Leet Code OJ 70. Climbing Stairs(爬楼梯问题)
- Leetocode之Task Scheduler 问题
- lintcode 中等题:A + B Problem A + B 问题
- Leetcode Tree Problem 树问题合集
- Google Code Jam 2010 Qualification Round 资格赛 Problem A. Snapper Chain 问题A.按扣链条
- Chef and Prime Divisors Problem code: CHAPD (GCD问题)
- Leet code problem 7: reverse integer digit
- leecode 解题总结:225. Implement Stack using Queues
- js问题合集