【ACM模式】栈的操作

求解代码

publicstaticvoidmain(String[]args)throwsIOException{BufferedReaderbr=newBufferedReader(newInputStreamReader(System.in));StreamTokenizerin=newStreamTokenizer(br);PrintWriterout=newPrintWriter(newOutputStreamWriter(System.out));Deque<Integer>stack=newArrayDeque<>();in.nextToken();intn=(int)in.nval;for(inti=0;i<n;i++){in.nextToken();Stringstr=(String)in.sval;switch(str){case"push":in.nextToken();stack.push((int)in.nval);break;case"pop":if(stack.isEmpty()){out.println("Empty");}else{stack.pop();}break;case"query":if(stack.isEmpty()){out.println("Empty");}else{out.println(stack.peek());}break;case"size":out.println(stack.size());break;default:break;}}out.flush();out.close();}

小贴士

官方文档明确标注：

Deque接口及其实现类（如ArrayDeque）应优先于Stack类使用。