const turtle = new Turtle();
const text = new Text();

const seed = 1; // min=1,max=255,step=1
const random = new Random(seed);
const replacements = random.shuffle(`ABC`.split(``));
const results = [];

const startA = (100+700 * random.next())|0;
const startB = (100+700 * random.next())|0;
const startC = (100+700 * random.next())|0;
loopA: for(let i=startA;i<999;i++) {
    let val1 = `${i}`;
    loopB: for(let j=startB;j<999;j++) {
        let val2 = `${j}`;
        if (check(val1, val2)) {
            loopC: for(let k=startC;k<999;k++) {
                let val3 = `${k}`;
                if (check(val1, val3) || check(val2, val3)) {
                    const answer = `${i+j+k}`;
                    if (check(val1, answer) && answer.length == 4) {
                        collect([val1,val2,val3,answer]);
                        if (results.length == 15) {
                            break loopA;
                            break loopB;
                            break loopC;
                        }
                    }
                }
            }
        }
    }
}

function collect(arr) {
    // random move first item to second or third pos
    var first = arr.shift();
    arr.splice(random.next() * 3 | 0, 0, first);
    
    
    const answer = arr.join(",");
    const ltrs = [];
    loopA: for(let val of arr) {
        const letters = val.split(``);
        loopB: for(let letter of letters) {
            if (ltrs.indexOf(letter) < 0) {
                ltrs.push(letter);
                if (ltrs.length === 3) {
                    break loopA;
                    break loopB;
                }
            }   
        }
    }
    for (let i=0;i<arr.length;i++) {
        for(let j=0;j<3;j++) {
            arr[i] = arr[i].split(ltrs[j]).join(replacements[j]);
        }
    }
    const question = arr.join(",");
    if (results.indexOf(question) < 0) {
        results.push({question,answer});
    }
}

function check(a, b) {
    const letters = b.split(``);
    for(let letter of letters) {
        if (a.indexOf(letter) < 0) {
            return false;
        }
    }
    return true;
}


// The walk function will be called until it returns false.
function walk() {
    const selection = results[random.next() * results.length | 0];
    const showAnswer = 0; //min=0,max=1,step=1
    const lines = (showAnswer ? selection.answer : selection.question).split(",");
    for(let i=0;i<lines.length;i++) {
        const y = -50 + i * 30;
        const line = lines[i];
        if (i < 3) {
            turtle.jump(-50, y);
            text.print(turtle, " " + line, 1);
        } else {
            // line
            turtle.jump(-50, y - 10);
            turtle.goto(50,  y - 10);
            
            // +
            turtle.jump(60, y - 10);
            text.print(turtle, "+", 1);
            
            
            turtle.jump(-50, y + 10);
            text.print(turtle, line, 1);
        }
    }
}


////////////////////////////////////////////////////////////////
// Text utility code. Created by Reinder Nijhoff 2019
// https://turtletoy.net/turtle/1713ddbe99
////////////////////////////////////////////////////////////////
function Text() {
    class Text {
        print (t, str, scale = 1, italic = -.075, kerning = 1.25) {
            t.radians();
            let pos = [t.x(), t.y()], h = t.h(), o = pos;
            str.split('').map(c => {
                const i = c.charCodeAt(0) - 32;
                if (i < 0 ) {
                    pos = o = this.rotAdd([0, 48*scale], o, h);
                } else if (i > 96 ) {
                    pos = this.rotAdd([16*scale, 0], o, h);
                } else {
                    const d = dat[i], lt = d[0]*scale, rt = d[1]*scale, paths = d[2];
                    paths.map( p => {
                        t.up();
                    	p.map( s=> {
                        	t.goto(this.rotAdd([(s[0]-s[1]*italic)*scale - lt, s[1]*scale], pos, h));
                        	t.down();
                        });
                    });
                    pos = this.rotAdd([(rt - lt)*kerning, 0], pos, h);
                }
            });
        }
        rotAdd (a, b, h) {
            return [Math.cos(h)*a[0] - Math.sin(h)*a[1] + b[0], 
                    Math.cos(h)*a[1] + Math.sin(h)*a[0] + b[1]];
        }
    }
    
const dat = ('br>eoj^jl<jqirjskrjq>brf^fe<n^ne>`ukZdz<qZjz<dgrg<cmqm>`thZhw<lZlw<qao_l^h^e_caccdeefg'+
'gmiojpkqmqporlshsercp>^vs^as<f^h`hbgdeeceacaab_d^f^h_k`n`q_s^<olmmlolqnspsrrspsnqlol>]wtgtfsereqfph'+
'nmlpjrhsdsbraq`o`makbjifjekckaj_h^f_eaecffhimporqssstrtq>eoj`i_j^k_kajcid>cqnZl\\j_hcghglhqjulxnz>c'+
'qfZh\\j_lcmhmllqjuhxfz>brjdjp<egom<ogem>]wjajs<ajsj>fnkojpiojnkokqis>]wajsj>fnjniojpkojn>_usZaz>`ti'+
'^f_dbcgcjdofrisksnrpoqjqgpbn_k^i^>`tfbhak^ks>`tdcdbe`f_h^l^n_o`pbpdofmicsqs>`te^p^jfmfogphqkqmppnrk'+
'shserdqco>`tm^clrl<m^ms>`to^e^dgefhekenfphqkqmppnrkshserdqco>`tpao_l^j^g_ebdgdlepgrjsksnrppqmqlping'+
'kfjfggeidl>`tq^gs<c^q^>`th^e_dadceegfkgnhpjqlqopqorlshserdqcocldjfhigmfoepcpao_l^h^>`tpeohmjjkikfjd'+
'hcecddaf_i^j^m_oapepjoomrjshserdp>fnjgihjikhjg<jniojpkojn>fnjgihjikhjg<kojpiojnkokqis>^vrabjrs>]wag'+
'sg<amsm>^vbarjbs>asdcdbe`f_h^l^n_o`pbpdofngjijl<jqirjskrjq>]xofndlcicgdfeehekfmhnknmmnk<icgefhfkgmh'+
'n<ocnknmpnrntluiugtdsbq`o_l^i^f_d`bbad`g`jambodqfrislsorqqrp<pcokompn>asj^bs<j^rs<elol>_tc^cs<c^l^o'+
'_p`qbqdpfoglh<chlhoipjqlqopqorlscs>`urcqao_m^i^g_eadccfckdnepgrismsorqprn>_tc^cs<c^j^m_oapcqfqkpnop'+
'mrjscs>`sd^ds<d^q^<dhlh<dsqs>`rd^ds<d^q^<dhlh>`urcqao_m^i^g_eadccfckdnepgrismsorqprnrk<mkrk>_uc^cs<'+
'q^qs<chqh>fnj^js>brn^nnmqlrjshsfreqdndl>_tc^cs<q^cl<hgqs>`qd^ds<dsps>^vb^bs<b^js<r^js<r^rs>_uc^cs<c'+
'^qs<q^qs>_uh^f_daccbfbkcndpfrhslsnrppqnrkrfqcpan_l^h^>_tc^cs<c^l^o_p`qbqepgohlici>_uh^f_daccbfbkcnd'+
'pfrhslsnrppqnrkrfqcpan_l^h^<koqu>_tc^cs<c^l^o_p`qbqdpfoglhch<jhqs>`tqao_l^h^e_caccdeefggmiojpkqmqpo'+
'rlshsercp>brj^js<c^q^>_uc^cmdpfrisksnrppqmq^>asb^js<r^js>^v`^es<j^es<j^os<t^os>`tc^qs<q^cs>asb^jhjs'+
'<r^jh>`tq^cs<c^q^<csqs>cqgZgz<hZhz<gZnZ<gznz>cqc^qv>cqlZlz<mZmz<fZmZ<fzmz>brj\\bj<j\\rj>asazsz>fnkc'+
'ieigjhkgjfig>atpeps<phnfleiegfehdkdmepgrislsnrpp>`sd^ds<dhffhekemfohpkpmopmrkshsfrdp>asphnfleiegfeh'+
'dkdmepgrislsnrpp>atp^ps<phnfleiegfehdkdmepgrislsnrpp>asdkpkpiognfleiegfehdkdmepgrislsnrpp>eqo^m^k_j'+
'bjs<gene>atpepuoxnylzizgy<phnfleiegfehdkdmepgrislsnrpp>ate^es<eihfjemeofpips>fni^j_k^j]i^<jejs>eoj^'+
'k_l^k]j^<kekvjyhzfz>are^es<oeeo<ikps>fnj^js>[y_e_s<_ibfdegeifjijs<jimfoeretfuius>ateees<eihfjemeofp'+
'ips>atiegfehdkdmepgrislsnrppqmqkphnfleie>`sdedz<dhffhekemfohpkpmopmrkshsfrdp>atpepz<phnfleiegfehdkd'+
'mepgrislsnrpp>cpgegs<gkhhjfleoe>bsphofleieffehfjhkmlompopporlsisfrep>eqj^jokrmsos<gene>ateeeofrhsks'+
'mrpo<peps>brdejs<pejs>_ubefs<jefs<jens<rens>bseeps<pees>brdejs<pejshwfydzcz>bspees<eepe<esps>cqlZj['+
'i\\h^h`ibjckekgii<j[i]i_jakbldlfkhgjkllnlpkrjsiuiwjy<ikkmkojqirhthvixjylz>fnjZjz>cqhZj[k\\l^l`kbjci'+
'eigki<j[k]k_jaibhdhfihmjilhnhpirjskukwjy<kkimiojqkrltlvkxjyhz>^vamakbhdgfghhlknlplrksi<akbidhfhhill'+
'nmpmrlsisg>brb^bscsc^d^dsese^f^fsgsg^h^hsisi^j^jsksk^l^lsmsm^n^nsoso^p^psqsq^r^rs').split('>').map(
    r=> { return [r.charCodeAt(0)-106,r.charCodeAt(1)-106, r.substr(2).split('<').map(a => {const ret 
    = []; for (let i=0; i<a.length; i+=2) {ret.push(a.substr(i, 2).split('').map(b => b.charCodeAt(0)
    -106));} return ret; })]; });

    return new Text();
}

// Seeded random - Mulberry32
function Random(seed) {
    class Random {
        constructor(seed) { 
            this.seed = seed;
        }
        next() { 
            var t = this.seed += 0x6D2B79F5;
            t = Math.imul(t ^ t >>> 15, t | 1);
            t ^= t + Math.imul(t ^ t >>> 7, t | 61);
            return ((t ^ t >>> 14) >>> 0) / 4294967296;
        }
        shuffle(arr) {
            for (let i = arr.length - 1; i > 0; i--) {
                const j = Math.floor(this.next() * (i + 1));
                [arr[i], arr[j]] = [arr[j], arr[i]];
            }
            return arr;
        }
    }
    return new Random(seed);
}