function firstNonRepeatingLetter(s) {? var str=new Array();? str=s.split("");? ? for(var i=0;i<str.lenght;i++){??? if(s.indexOf(str[i])==s.lastIndexOf(str[i])){??? return str[i];??? }? }? }
為什么retrun都是undefined?
Herald523
2017-01-12 14:25:22