app手机电视网站设计方案,wordpress怎么上手,做网站 多页面网址怎么弄,做生物卷子的网站提示#xff1a;文章写完后#xff0c;目录可以自动生成#xff0c;如何生成可参考右边的帮助文档 文章目录 前言一、力扣20. 有效的括号二、力扣1047. 删除字符串中的所有相邻重复项三、力扣150. 逆波兰表达式求值 前言 一、力扣20. 有效的括号
class Solution {public bo… 提示文章写完后目录可以自动生成如何生成可参考右边的帮助文档 文章目录 前言一、力扣20. 有效的括号二、力扣1047. 删除字符串中的所有相邻重复项三、力扣150. 逆波兰表达式求值 前言 一、力扣20. 有效的括号
class Solution {public boolean isValid(String s) {DequeCharacter deq new ArrayDeque();for(int i 0; i s.length(); i ){if(s.charAt(i) ( || s.charAt(i) [ || s.charAt(i) {){deq.offerLast(s.charAt(i));}else{if(deq.isEmpty()){return false;}char temp deq.pollLast();if(s.charAt(i) ) temp ! (){return false;}if(s.charAt(i) ] temp ! [){return false;}if(s.charAt(i) } temp ! {){return false;}}}return deq.isEmpty();}
}二、力扣1047. 删除字符串中的所有相邻重复项
class Solution {public String removeDuplicates(String s) {DequeCharacter deq new ArrayDeque();StringBuilder sb new StringBuilder();for(int i 0; i s.length(); i ){if(deq.isEmpty()){deq.offerFirst(s.charAt(i));}else{if(deq.peekFirst() s.charAt(i)){deq.pollFirst();}else{deq.offerFirst(s.charAt(i));}}}while(!deq.isEmpty()){sb.append(deq.pollLast());}return sb.toString();}
}三、力扣150. 逆波兰表达式求值
class Solution {public int evalRPN(String[] tokens) {DequeInteger deq new ArrayDeque();for(int i 0; i tokens.length; i ){if(.equals(tokens[i])){int right deq.pollFirst();int left deq.pollFirst();deq.offerFirst(left right);}else if(-.equals(tokens[i])){int right deq.pollFirst();int left deq.pollFirst();deq.offerFirst(left - right);}else if(*.equals(tokens[i])){int right deq.pollFirst();int left deq.pollFirst();deq.offerFirst(left * right);}else if(/.equals(tokens[i])){int right deq.pollFirst();int left deq.pollFirst();deq.offerFirst(left / right);}else{deq.offerFirst(Integer.parseInt(tokens[i]));}}return deq.pollFirst();}
}
