数组的集合运算

set={
    uniq:function(s){//去重
        var r=[];
        for(var i=0;i<s.length;i++){
            if(s.indexOf(s[i])==i) r.push(s[i]);
        };
        return r;
    },
    d:function(s1,s2){//差集
        var b=this.uniq(s1);
        var a=this.uniq(s2);
        return b.filter(v => !a.includes(v));
    },
    u:function(s1,s2){//并集
        var b=this.uniq(s1);
        var a=this.uniq(s2);
        return this.uniq(a.concat(b));
    },
    n:function(s1,s2){//交集
        var b=this.uniq(s1);
        var a=this.uniq(s2);
        return b.filter(v => a.includes(v));
    },
    in:function(s1,s2){//是否是子集
        var b=this.uniq(s1);
        var a=this.uniq(s2);
        var c=this.n(b,a);
        return b.length==c.length;
    }
};