两全局数组
//Init module if you need function Init() { // write code here //全局声明 arr=[]//存放只出现一次的字符 res='' temp=[]//存放出现多处的字符 } //Insert one char from stringstream function Insert(ch) { let newCh=ch if(ch!='/n'||ch!=null){ this.res+=this.FirstAppearingOnce(ch) }else{ console.log(this.res) } } //return the first appearence once char in current stringstream function FirstAppearingOnce(ch) { // write code here if(this.arr.includes(ch)){ this.temp.push(ch) this.arr.splice(this.arr.indexOf(ch),1); }else if(!(this.temp.includes(ch))){ this.arr.push(ch); } return this.arr.length==0?'#':this.arr[0] }