档案日期2015的49

题目描述：

Given a string which contains only lowercase letters, remove duplicate letters so that every letter appear once and only once. You must make sure your result is the smallest in lexicographical order among all possible results.

Example:

Given "bcabc" ...

代码参考：http://jsfiddle.net/amcharts/ATQUm/

JavaScript代码：

var chart;
var chartData = [];
var chartCursor;
var day = 0;
var firstDate = new Date();
firstDate.setDate(firstDate.getDate() - 500);

// generate some random data, quite different range
function generateChartData() {
    for (day = 0; day < 50 ...