08.md

集合

集合是什么

1. 集合是一种包含不同元素的数据结构
2. 集合成员是无序的，集合成员不能重复
3. 集合有，空集、交集、并集、补集

集合

function Set() {
  this.store = [];
  this.add = add;
  this.remove = remove;
  this.size = size;
  this.union = union;
  this.intersect = intersect;
  this.difference = difference;
  this.show = show;
  this.subset = subset;
}
let add = function(data) {
  if (this.store.indexOf(data) === -1) {
    this.store.push(data);
  }
};
let remove = function(data) {
  var index = this.store.indexOf(data);
  if (index > 0) {
    this.store.splice(index, 1);
  }
};
let size = function() {
  return this.store.length;
};
// 并集
let union = function(set) {
  var s = new Set();
  for (var i = 0; i < this.store.length; i++) {
    s.add(this.store[i]);
  }
  for (var i = 0; i < set.store.length; i++) {
    var index = s.store.indexOf(set.store[i]);
    if (index === -1) {
      s.add(set.store[i]);
    }
  }
  return s;
};
// 交集
let intersect = function(set) {
  var s = new Set();
  for (var i = 0; i < set.store.length; i++) {
    if (this.store.indexOf(set.store[i]) !== -1) {
      s.add(set.store[i]);
    }
  }
  return s;
};
// 补集
let difference = function(set) {
  var s = new Set();
  for (var i = 0; i < this.store.length; i++) {
    var index = set.store.indexOf(this.store[i]);
    if (index === -1) {
      s.add(this.store[i]);
    }
  }
  return s;
};
let show = function() {
  return this.store.toString();
};
// 是否是子集
let subset = function(set) {
  if (set.size() > this.size()) {
    return false;
  } else {
    for (var i = 0; i < set.store.length; i++) {
      if (this.store.indexOf(set.store[i]) === -1) {
        return false;
      }
    }
    return true;
  }
};
var s = new Set();
s.add(1);
s.add(2);
s.add(3);
s.add(4);
s.add(5);
console.log(s.show());
s.remove(2);
console.log(s.show());

var s2 = new Set();
s2.add(11);
s2.add(11);
s2.add(22);
s2.add(33);
s2.add(1);
s2.add(5);
console.log("s2-》", s2.show());

console.log("并集", s.union(s2).show());
console.log("交集", s.intersect(s2).show());
console.log("s2相对s补集(s有的,s2没有)", s.difference(s2).show());

var s3 = new Set();
s3.add(11);
s3.add(1);
s3.add(22);
s3.add(22);
s3.add(1);
console.log(s3.show());
console.log("s3是s2的子集", s2.subset(s3));