cupido

function random_impl (state) {
    var x = state.a|0;
    x = x^(x<<13);
    x = x^(x>>17);
    x = x^(x<<5);
    return state.a=(x|0);
}

function random (state) {
    return random_impl(state) / 2**32 + 0.5;
}

function good_table (
    table,
    cases
) {
    var random_state = {a: 260526127};
    var badness = 0;
    for(var j = 0; j < cases.length; j++){
        badness += (dumb_cupid(table, cases[j][0], cases[j][1])-cases[j][2])**2;
    }
    for(var i = 0; i < 5000; i++){
        var letters = "abcdefghijklmnopqrstuvwxyz";
        var letter = letters[Math.floor(random(random_state)*26)];
        var change = (random(random_state)*2-1) * 0.05;
        var old = table[letter];
        table[letter] += change;

        var new_bad = 0;
        for(var j = 0; j < cases.length; j++){
            new_bad += (dumb_cupid(table, cases[j][0], cases[j][1])-cases[j][2])**2;
        }

        if(new_bad < badness){
            badness = new_bad;
        }else{
            table[letter] = old;
        }
    }
}

function dumb_cupid (letter_table, name_1, name_2) {
    name_1 = name_1.toLowerCase();
    name_2 = name_2.toLowerCase();

    var score = 0;

    if(name_1 == name_2){
        return score;
    }

    var n1fl = name_1[0];
    var n2fl = name_2[0];
    if(n1fl == n2fl){
        score += letter_table[n1fl] * 5;
    }
    for(var i = 0; i < name_1.length; i++){
        if( i >= name_2.length) break;

        n1fl = name_1[i];
        n2fl = name_2[i];

        var k = (name_1.length-i);
        var sum = 0;
        for(var j = 0; j < name_1.length; j++){
            sum += (name_1.length-j);
        }
        k /= sum;
        if(name_2.length < name_1.length){
            k = (name_2.length-i);
            var sum = 0;
            for(var j = 0; j < name_2.length; j++){
                sum += (name_2.length-j);
            }
            k /= sum;
        }

        score += (letter_table[n1fl] + letter_table[n2fl]) / 2 * k * 95;
    }

    return score;
}

function cupid (name_1, name_2) {
    name_1 = name_1.toLowerCase();
    name_2 = name_2.toLowerCase();
    var cases = [
        ["Romeo", "Juliet", 95],
        ["Jack", "Rose", 32]
    ];
    var letter_table = {
        'a': 0.5, 'b': 0.5, 'c': 0.5, 'd': 0.5,
        'e': 1.0, 'f': 0.5, 'g': 0.5, 'h': 0.5,
        'i': 1.0, 'j': 1.0, 'k': 0.5, 'l': 1.0,
        'm': 1.0, 'n': 0.5, 'o': 1.0, 'p': 0.5,
        'q': 0.5, 'r': 1.0, 's': 0.5, 't': 1.0,
        'u': 1.0, 'v': 0.5, 'w': 0.5, 'x': 0.5,
        'y': 0.5, 'z': 0.5,
    };
    good_table(letter_table, cases);

    var score = 0;

    if(name_1 == name_2){
        return score;
    }

    var n1fl = name_1[0];
    var n2fl = name_2[0];
    if(n1fl == n2fl){
        score += letter_table[n1fl] * 5;
    }
    for(var i = 0; i < name_1.length; i++){
        if( i >= name_2.length) break;

        n1fl = name_1[i];
        n2fl = name_2[i];

        var k = (name_1.length-i);
        var sum = 0;
        for(var j = 0; j < name_1.length; j++){
            sum += (name_1.length-j);
        }
        k /= sum;
        if(name_2.length < name_1.length){
            k = (name_2.length-i);
            var sum = 0;
            for(var j = 0; j < name_2.length; j++){
                sum += (name_2.length-j);
            }
            k /= sum;
        }

        score += (letter_table[n1fl] + letter_table[n2fl]) / 2 * k * 95;
    }

    return score;
}

function test (name_1, name_2) {
    console.log(`${name_1}, ${name_2} => ${cupid(name_1, name_2)}`);
}

test("Romeo", "Juliet");
test("Jack", "Rose");