/*js集合set类的实现*/
function Set() {
  this.dataStore = [];
  this.add = add;//新增元素
  this.remove = remove;//删除元素
  this.size = size;//集合的元素个数
  this.union = union;//求并集
  this.contains = contains;//判断一个集合中是否包含某个元素
  this.intersect = intersect;//交集
  this.subset = subset;//判断一个集合是否是另一个的子集
  this.difference = difference;//求补集
  this.show = show;//将集合元素显示出来
}
function add(data) {
  if (this.dataStore.indexOf(data) < 0) {
    this.dataStore.push(data);
    return true;
  }
  else {
    return false;
  }
}
function remove(data) {
  var pos = this.dataStore.indexOf(data);
  if (pos > -1) {
    this.dataStore.splice(pos,1);
    return true;
  }
  else {
    return false;
  }
}
function size() {
  return this.dataStore.length;
}
function show() {
  return "[" + this.dataStore + "]";
}
function contains(data) {
  if (this.dataStore.indexOf(data) > -1) {
    return true;
  }
  else {
    return false;
  }
}
function union(set) {
  var tempSet = new Set();
  for (var i = 0; i < this.dataStore.length; ++i) {
    tempSet.add(this.dataStore[i]);
  }
  for (var i = 0; i < set.dataStore.length; ++i) {
    if (!tempSet.contains(set.dataStore[i])) {
      tempSet.dataStore.push(set.dataStore[i]);
    }
  }
  return tempSet;
}
function intersect(set) {
  var tempSet = new Set();
  for (var i = 0; i < this.dataStore.length; ++i) {
    if (set.contains(this.dataStore[i])) {
      tempSet.add(this.dataStore[i]);
    }
  }
  return tempSet;
}
function subset(set) {
  if (this.size() > set.size()) {
    return false;
  }
  else {
    for(var member in this.dataStore) {
      if (!set.contains(member)) {
        return false;
      }
    }
  }
  return true;
}
function difference(set) {
  var tempSet = new Set();
  for (var i = 0; i < this.dataStore.length; ++i) {
    if (!set.contains(this.dataStore[i])) {
      tempSet.add(this.dataStore[i]);
    }
  }
  return tempSet;
}
/*测试例子：求补集。属于集合cis,不属于集合it*/
var cis = new Set();
var it = new Set();
cis.add("Clayton");
cis.add("Jennifer");
cis.add("Danny");
it.add("Bryan");
it.add("Clayton");
it.add("Jennifer");
var diff = new Set();
diff = cis.difference(it);
console.log(cis.show() + " difference " + it.show() + " -> " + diff.show());