数据结构于JS也可以成为CP（八）集合

function Set() {
  this.dataStore = [];
  this.add = add;
  this.remove = remove;
  this.size = size;
  this.union = union;
  this.intersect = intersect;
  this.subset = subset;
  this.difference = difference;
  this.show = show;
}
//我们知道set中不能存在重复值，所以add函数需要首先检查数组中是否已存在该元素
function add(data) {
  if (this.dataStore.indexOf(data) < 0) {
     this.dataStore.push(data);
     return true;
  }
  else {
     return false;
  } 
}
//remove则要先检查是否存在，存在再删除
function remove(data) {
  var pos = this.dataStore.indexOf(data);
  if (pos > -1) {
     this.dataStore.splice(pos,1);
     return true;
  }
  else {
     return false;
  } 
}
function show() {
  return this.dataStore;
}
function contains(data) {
  if (this.dataStore.indexOf(data) > -1) {
     return true;
  }
  else {
     return false;
  } 
}
//并集
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;
}
//交集
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;
}
//子集
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 size() {
  return this.dataStore.length;
}
//属于第一个集合，但不属于第二个集合
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;
}