pairs_with_given_difference.js

//TODO: compare output with the crude version
function pairs (k, arr) {
    let map = {};
    arr.forEach (x=> map[x] = 1);
    let result = 0;
    arr.sort();
    arr.forEach(x=> 
        {
            let diff = k + x;
            if (map[diff] == 1) {
                result +=1;
            }
        }
    );
    return result;
}
console.assert(pairs(687, [967551, 42711, 652888, 556131, 432461, 689084, 878716, 707516, 462627, 719131, 921983, 626364, 4162, 381455, 628368, 434733, 845482, 789342, 129922, 384203, 516975, 872544, 958157, 257969, 383516, 972027, 753530, 579132, 732314, 692990, 938898, 673695, 304274, 911598, 386363, 643777, 897942, 705604, 307205, 691832, 525153, 13560, 131633, 967903, 704917, 719007, 275998, 823133, 381356, 694812, 130946, 14247, 881464, 212321, 535615, 388113, 263786, 993408, 303132, 347246, 957012, 356253, 80278, 682192, 79591, 22168, 399471, 130259, 302213, 146877, 143512, 464001, 323710, 716383, 252562, 704230, 528752, 385676, 433835, 84087, 324397, 19622, 726853, 400158, 765711, 879403, 717070, 796189, 630429, 735240, 899316, 897255, 682879, 943532, 548896, 650909, 128885, 156561, 260454, 861309, 463314, 396080, 486644, 483429, 306518, 579819, 726166, 319856, 689771, 346559, 466803, 340669, 602785, 686432, 259959, 146736, 878107, 718444, 272951, 371357, 690458, 625990, 672321, 968982, 211634, 966184, 806955, 421135, 486063, 350431, 856525, 674382, 968295, 709010, 81652, 874036, 487437, 966921, 318376, 402219, 956325, 319682, 346722, 112336, 643090, 670617, 700593, 580506, 695051, 996996, 486750, 989387, 738565, 873231, 311817, 351118, 77220, 129572, 900003, 880777, 109146, 675069, 829732, 420069, 519779, 692670, 391266, 683566, 349744, 629055, 305831, 14934, 216260, 302900, 347933, 85417, 307892, 367031, 433148, 431774, 871170, 955638, 629386, 252687, 151756, 290426, 642403, 213008, 693677, 349307, 80965, 376767, 879481, 177826, 382142, 591034, 733001, 967608, 381793, 957699, 382829, 251634, 641716, 226476, 530957, 871857, 658236, 615467, 401532, 681505, 485376, 694364, 144675, 23169, 673008, 146049, 581193, 461940, 22324, 641029, 878794, 620846, 558429, 6994, 41576, 717757]) == 80);
console.assert(pairs(2, [1,2,3,4,5,6,8]) == 5);
console.assert(pairs(1, [363374326, 364147530, 61825163, 1073065718, 1281246024, 1399469912, 428047635, 491595254, 879792181, 1069262793]) == 0);
console.assert(pairs(2, [1, 5, 3, 4, 2]) == 3);