var arrs = [];
arrs.push("a");
arrs.push("b");
console.log(arrs); // ["a","b"];
arrs.shift();
console.log(arrs); // ['b'];

function Queue() {
  this.dataStore = [];
}

function enqueue(element) {
   this.dataStore.push(element);
}

function dequeue() {
  return this.dataStore.shift()
}

function front() {
  return this.dataStore[0];
}

function back() {
  return this.dataStore[this.dataStore.length - 1];
}

function toString() {
  var retStr = "";
  for(var i = 0; i < this.dataStore.length; ++i) {
    retStr += this.dataStore[i] + "\n";
  }
  return retStr;
}

function empty(){
  if(this.dataStore.length == 0) {
    return true;
  }else {
    return false;
  }
}

function Queue() {
  this.dataStore = [];
}
Queue.prototype = {
  // 向队尾添加一个元素
  enqueue: function(element) {
    this.dataStore.push(element);
  },
  // 删除队首的元素
  dequeue: function(){
    return this.dataStore.shift();
  },
  // 读取队首的元素
  front: function(){
    return this.dataStore[0];
  },
  // 读取队尾的元素
  back: function(){
    return this.dataStore[this.dataStore.length - 1];
  },
  // 显示队列内的所有元素
  toString: function(){
    var retStr = "";
    for(var i = 0; i < this.dataStore.length; ++i) {
      retStr += this.dataStore[i] + "\n";
    }
    return retStr;
  },
  // 判断队列是否为空
  empty: function(){
    if(this.dataStore.length == 0) {
      return true;
    }else {
      return false;
    }
  }
};

var q = new Queue();
q.enqueue("a");
q.enqueue("b");
q.enqueue("c");
console.log(q.toString()); // a b c
q.dequeue();
console.log(q.toString()); // b c
console.log("Front of queue:" +q.front()); // b
console.log("Back of queue:" +q.back()); // c

var nums = ["50","12","95","7","90","3","74","81","91","72"];

queues[0] = 50 或者 90
queues[1] = 81 或者 91
queues[2] = 12 或者 72
queues[3] = 3
queues[4] = 74
queues[5] = 95
queues[6] 
queues[7] = 7
queues[8]
queues[9]

nums = [50,90,81,91,12,72,3,74,95,7]

queues[5] = 50
queues[9] = 90
queues[8] = 81
queues[9] = 91
queues[1] = 12
queues[7] = 72
queues[0] = 3
queues[7] = 74
queues[9] = 95
queues[0] = 7

nums = [3,7,12,50,72,74,81,90,91,95];

/*
* 根据个位或十位上的数值，将数字分配到相应队列的函数
* @param digit
* digit=1 表示先按个位来分配
* digit = 10 表示是按十位来分配的
* @param n 表示循环比较多少次 一般数组几个数字就比较多少次
*/
distribute: function(nums,queues,n,digit){
   for(var i = 0; i < n; ++i) {
    if(digit == 1) {
      queues[nums[i] % 10].enqueue(nums[i]);
     }else {
      queues[Math.floor(nums[i] / 10)].enqueue(nums[i]);
     }
   }
}

// 收集数字的函数
collect: function(queues,nums,n) {
  var i = 0;
  for(var digit = 0; digit < n; ++digit) {
    while(!queues[digit].empty()) {
      nums[i++] = queues[digit].dequeue();
    }
  }
}

function Queue() {
  this.dataStore = [];
}
Queue.prototype = {
  // 向队尾添加一个元素
  enqueue: function(element) {
    this.dataStore.push(element);
  },
  // 删除队首的元素
  dequeue: function(){
    return this.dataStore.shift();
  },
  // 读取队首的元素
  front: function(){
    return this.dataStore[0];
  },
  // 读取队尾的元素
  back: function(){
    return this.dataStore[this.dataStore.length - 1];
  },
  // 显示队列内的所有元素
  toString: function(){
    var retStr = "";
    for(var i = 0; i < this.dataStore.length; ++i) {
      retStr += this.dataStore[i] + "\n";
    }
    return retStr;
  },
  // 判断队列是否为空
  empty: function(){
    if(this.dataStore.length == 0) {
      return true;
    }else {
      return false;
    }
  },
  /*
   * 根据个位或十位上的数值，将数字分配到相应队列的函数
   * @param digit
   * digit=1 表示先按个位来分配
   * digit = 10 表示是按十位来分配的
   * @param n 表示循环比较多少次 一般数组几个数字就比较多少次
   */
  distribute: function(nums,queues,n,digit){
    for(var i = 0; i < n; ++i) {
      if(digit == 1) {
        queues[nums[i] % 10].enqueue(nums[i]);
      }else {
        queues[Math.floor(nums[i] / 10)].enqueue(nums[i]);
      }
    }
  },
  // 收集数字的函数
  collect: function(queues,nums,n) {
    var i = 0;
    for(var digit = 0; digit < n; ++digit) {
      while(!queues[digit].empty()) {
        nums[i++] = queues[digit].dequeue();
      }
    }
  },
  dispArray: function(arr) {
    for(var i = 0; i < arr.length; ++i) {
      console.log(arr[i]);
    }
  }
};

var q = new Queue();
  q.enqueue("a");
  q.enqueue("b");
  q.enqueue("c");
console.log(q.toString());
q.dequeue();
console.log(q.toString());
console.log("Front of queue:" +q.front());
console.log("Back of queue:" +q.back());
var queues = [];
for(var i = 0; i < 10; ++i) {
   queues[i] = new Queue();
}
var nums = ["50","12","95","7","90","3","74","81","91","72"];
console.log("before radix sort: ");
console.log(nums);
q.distribute(nums,queues,10,1);
q.collect(queues,nums,10);
q.dispArray(nums);
console.log("分割线");
q.distribute(nums,queues,10,10);
q.collect(queues,nums,10);
q.dispArray(nums);