function reduce(numerator,denominator){
  var gcd = function gcd(a,b){
    return b ? gcd(b, a%b) : a;
  };
  gcd = gcd(numerator,denominator);
  return [numerator/gcd, denominator/gcd];
}

function spamDetection(messages, spamSignals) {
    let res = ["passed","","passed","passed"], message, user, msgByUsr = {}, fewerThan5 = 0, contain = 0, contWords = [];
    Array.prototype.unique = function() {
        var a = this.concat();
        for(var i=0; i<a.length; ++i) {
            for(var j=i+1; j<a.length; ++j) {
                if(a[i] === a[j])
                    a.splice(j--, 1);
            }
        }

        return a;
    };
    for(let i = 0; i<messages.length; i++){
        message = messages[i][0];
        user = messages[i][1];

        // Check less than 5 words
        if(message.split(" ").length<5) fewerThan5++;

        // Check 50% has the same content from the same user
        if(msgByUsr[user] !== undefined){
            if(msgByUsr[user][message] !== undefined) msgByUsr[user][message]++;
            else msgByUsr[user][message] = 1;
        }
        else{
            msgByUsr[user] = {};
            msgByUsr[user][message] = 1;
        }



        // Contain suspicious word
        for(let j = 0; j<spamSignals.length; j++){
            if(message.replace(/[^a-z^\ ]/gi, ' ').toLowerCase().split(" ").indexOf(spamSignals[j]) != -1 ){
                contain++;
                // if(contWords[spamSignals[j]] === undefined) contWords[spamSignals] = 0
                contWords.push(spamSignals[j]);
            }
        }


    }
    console.log(msgByUsr);
    let frac = reduce(fewerThan5, messages.length)
    if(fewerThan5/messages.length > 0.9) res[0] = "failed: "+frac[0]+"/"+frac[1];


    let amount = 0, max = -1, maxAll = -1, amountAll = 0, maxMsg, maxMsgAll;
    Object.keys(msgByUsr).forEach(function(key1){
        amount = 0; max = -1;
        Object.keys(msgByUsr[key1]).forEach(function(key2){
            amount += msgByUsr[key1][key2];
            if(max < msgByUsr[key1][key2]){
                max = msgByUsr[key1][key2];
                maxMsg = key2;
                if(!maxMsgAll){
                    maxMsgAll = maxMsg;
                    maxAll = max;
                }
            }

        });
        amountAll += amount;
        if(maxMsgAll === maxMsg)
                maxAll += max;
        else{
            if(max < maxAll){
                maxAll = max;
                maxMsgAll = maxMsg;
            }
        }
        if(amount >= 2 && max/amount > 0.5) {
            res[1] += " "+key1;
        }
    });
    if(res[1] !== "") res[1] = "failed:"+res[1];
    else res[1] = "passed";
    if(amountAll >= 2 && maxAll/amountAll > 0.5)
        res[2] = "failed: "+maxMsgAll;

    if(messages.length >= 2 && contain>messages.length/2){
        res[3] = "failed: "+contWords.unique().sort().join(" ");
    }
    return res;
}