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binarySearch.js
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binarySearch.js
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/*
Binary Search
- Only works when given list is in a sorted order.
- Works by dividing the list in half and comparing the key to the middle element.
- If the key is equal to the middle element, the search is successful.
- If the key is less than the middle element, the search continues on the left side of the list.
- If the key is greater than the middle element, the search continues on the right side of the list.
- If the key is not found, the search is unsuccessful.
- The number of steps taken to find the key is the number of steps taken to find the middle element.
*/
const list = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,
36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59,
60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71,
72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83,
84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95,
96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106,
107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117,
118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128,
129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139,
140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150,
151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161,
162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172,
173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183,
184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194,
195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205,
206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216,
217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227,
228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238,
239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 249,
250, 251, 252, 253, 254, 255, 256, 257, 258, 259, 260,
261, 262, 263, 264, 265, 266, 267, 268, 269, 270, 271,
272, 273, 274, 275, 276, 277, 278, 279, 280, 281, 282,
283, 284, 285, 286, 287, 288, 289, 290, 291, 292, 293,
294, 295, 296, 297, 298, 299, 300, 301, 302, 303, 304,
305, 306, 307, 308, 309, 310, 311, 312, 313, 314, 315,
316, 317, 318, 319, 320, 321, 322, 323, 324, 325, 326,
327, 328, 329, 330, 331, 332, 333, 334, 335, 336, 337,
338, 339, 340, 341, 342, 343, 344, 345, 346, 347, 348,
349, 350, 351, 352, 353, 354, 355, 356, 357, 358, 359,
360, 361, 362, 363, 364, 365, 366, 367, 368, 369, 370,
371, 372, 373, 374, 375, 376, 377, 378, 379, 380, 381,
382, 383, 384, 385, 386, 387, 388, 389, 390, 391, 392,
393, 394, 395, 396, 397, 398, 399, 400, 401, 402, 403,
404, 405, 406, 407, 408, 409, 410, 411, 412, 413, 414,
415, 416, 417, 418, 419, 420, 421, 422, 423, 424, 425,
426, 427, 428, 429, 430, 431, 432, 433, 434, 435, 436,
437, 438, 439, 440, 441, 442, 443, 444, 445, 446, 447,
448, 449, 450, 451, 452, 453, 454, 455, 456, 457, 458,
459, 460, 461, 462, 463, 464, 465, 466, 467, 468, 469,
470, 471, 472, 473, 474, 475, 476, 477, 478, 479, 480,
481, 482, 483, 484, 485, 486, 487, 488, 489, 490, 491,
492, 493, 494, 495, 496, 497, 498, 499, 500, 501, 502,
503, 504, 505, 506, 507, 508, 509, 510, 511, 512, 513,
514, 515, 516, 517, 518, 519, 520, 521, 522, 523, 524,
525, 526, 527, 528, 529, 530, 531, 532, 533, 534, 535,
536, 537, 538, 539, 540, 541, 542, 543, 544, 545, 546,
547, 548, 549, 550, 551, 552, 553, 554, 555, 556, 557,
558, 559, 560, 561, 562, 563, 564, 565, 566, 567, 568,
569, 570, 571, 572, 573, 574, 575, 576, 577, 578, 579,
580, 581, 582, 583, 584, 585, 586, 587, 588, 589, 590,
591, 592, 593, 594, 595, 596, 597, 598, 599, 600, 601,
602, 603, 604, 605, 606, 607, 608, 609, 610, 611, 612,
613, 614, 615, 616, 617, 618, 619, 620, 621, 622, 623,
624, 625, 626, 627, 628, 629, 630, 631, 632, 633, 634,
635, 636, 637, 638, 639, 640, 641, 642, 643, 644, 645,
646, 647, 648, 649, 650, 651, 652, 653, 654, 655, 656,
657, 658, 659, 660, 661, 662, 663, 664, 665, 666, 667,
668, 669, 670, 671, 672, 673, 674, 675, 676, 677, 678,
679, 680, 681, 682, 683, 684, 685, 686, 687, 688, 689,
690, 691, 692, 693, 694, 695, 696, 697, 698, 699, 700,
701, 702, 703, 704, 705, 706, 707, 708, 709, 710, 711,
712, 713, 714, 715, 716, 717, 718, 719, 720, 721, 722,
723, 724, 725, 726, 727, 728, 729, 730, 731, 732, 733,
734, 735, 736, 737, 738, 739, 740, 741, 742, 743, 744,
745, 746, 747, 748, 749, 750, 751, 752, 753, 754, 755,
756, 757, 758, 759, 760, 761, 762, 763, 764, 765, 766,
767, 768, 769, 770, 771, 772, 773, 774, 775, 776, 777,
778, 779, 780, 781, 782, 783, 784, 785, 786, 787, 788,
789, 790, 791, 792, 793, 794, 795, 796, 797, 798, 799,
800, 801, 802, 803, 804, 805, 806, 807, 808, 809, 810,
811, 812, 813, 814, 815, 816, 817, 818, 819, 820, 821,
822, 823, 824, 825, 826, 827, 828, 829, 830, 831, 832,
833, 834, 835, 836, 837, 838, 839, 840, 841, 842, 843,
844, 845, 846, 847, 848, 849, 850, 851, 852, 853, 854,
855, 856, 857, 858, 859, 860, 861, 862, 863, 864, 865,
866, 867, 868, 869, 870, 871, 872, 873, 874, 875, 876,
877, 878, 879, 880, 881, 882, 883, 884, 885, 886, 887,
888, 889, 890, 891, 892, 893, 894, 895, 896, 897, 898,
899, 900, 901, 902, 903, 904, 905, 906, 907, 908, 909,
910, 911, 912, 913, 914, 915, 916, 917, 918, 919, 920,
921, 922, 923, 924, 925, 926, 927, 928, 929, 930, 931,
932, 933, 934, 935, 936, 937, 938, 939, 940, 941, 942,
943, 944, 945, 946, 947, 948, 949, 950, 951, 952, 953,
954, 955, 956, 957, 958, 959, 960, 961, 962, 963, 964,
965, 966, 967, 968, 969, 970, 971, 972, 973, 974, 975,
976, 977, 978, 979, 980, 981, 982, 983, 984, 985, 986,
987, 988, 989, 990, 991, 992, 993, 994, 995, 996, 997,
998, 999, 1000, 1001, 1002, 1003, 1004, 1005, 1006, 1007,
]
const binarySearch = (list, key) => {
let start = 0
let end = list.length - 1
let steps = {left: 0, right: 0}
while (start <= end) {
let middle = Math.floor((start + end) / 2)
if (list[middle] === key) {
console.log(`Found ${key} at index ${middle}`)
console.log("Steps to left:", steps.left)
console.log("Steps to right:", steps.right)
console.log(`Total steps: ${steps.left + steps.right}`)
return middle
} else if (list[middle] < key) {
steps.right++
start = middle + 1
} else {
steps.left++
end = middle - 1
}
}
return -1
}
console.log(binarySearch(list, 22))