first missing positive integer in an array using javascript?

Question

I am trying to find missing positive integer in an. array.I don't know where my function not working ?

question given

Given an unsorted integer array, find the first missing positive integer.

Given [1,2,0] return 3,

[3,4,-1,1] return 2,

[-8, -7, -6] returns 1

my function works on following above cases works fine..

let firstMissingPositive = function(A){
    if(A.length === 1 && A[0] < 0){
        return 1
    }
    let j=0;
    for (let i = 0; i < A.length; i++) {
        if(A[i] < 0){
            let temp = A[j]
             A[j] = A[i]
             A[i] = temp;
            j++;
        }
    }

    let arr =A.slice(j);
    for (let i = 0; i < arr.length; i++) {
        if (arr[(arr[i]) - 1] > 0) {
            arr[(arr[i]) - 1] = -arr[(arr[i]) - 1]
        }
    }
    let k=0;
    while (true){
        if(arr[k]>0 || k >= arr.length){
            break;
        }
        k++
    }
 return ++k
}

**but fails in this case ** when input is this.

[ 463, 127, 436, 72, 79, 301, 613, 898, 675, 960, 832, 486, 453, 274, 133, 721, 750, 538, 545, 112, 414, 817, 885, 812, 906, 577, 544, 101, 165, 45, 489, 503, 479, 293, 234, 427, 347, 851, 316, 827, 209, 578, 255, 56, 608, 914, 156, 537, 870, 567, 284, 240, 292, 111, 590, 713, 110, 768, 598, 879, 980, 660, 46, 320, 410, 869, 154, 970, 836, 423, 413, 501, 782, 403, 561, 117, 624, 638, 67, 646, 917, 379, 344, 543, 978, 506, 936, 947, 645, 633, 375, 706, 531, 470, 551, 632, 536, 642, 573, 705, 823, 897, 26, 476, 139, 496, 628, 91, 725, 570, 701, 244, 935, 126, 2, 560, 726, 20, 680, 7, 888, 183, 80, 804, 729, 583, 728, 515, 644, 774, 856, 192, 386, 25, 57, 471, 482, 174, 627, 757, 714, 203, 206, 847, 245, 336, 989, 326, 607, 95, 69, 71, 54, 975, 366, 591, 185, 964, 848, 84, 819, 737, 687, 215, 904, 651, 289, 134, 232, 341, 932, 64, 483, 128, 901, 808, 896, 941, 530, 195, 865, 903, 472, 508, 42, 971, 53, 86, 689, 925, 685, 934, 549, 841, 169, 317, 826, 600, 950, 90, 495, 219, 674, 814, 359, 556, 269, 187, 517, 541, 558, 8, 744, 958, 332, 163, 862, 218, 376, 23, 321, 346, 534, 864, 157, 285, 318, 200, 595, 810, 43, 32, 368, 753, 670, 887, 238, 1000, 513, 979, 499, 708, 473, 584, 981, 106, 695, 868, 881, 610, 273, 239, 190, 281, 373, 247, 364, 396, 837, 521, 871, 528, 617, 123, 894, 965, 108, 976, 451, 454, 673, 910, 681, 300, 702, 703, 307, 196, 535, 407, 763, 966, 945, 944, 65, 752, 776, 973, 554, 3, 998, 559, 35, -3, 147, 395, 761, 442, 586, 899, 191, 990, 606, 771, 393, 649, 987, 593, 877, 527, 201, 259, 150, 683, 263, 330, 21, 105, 406, 233, 303, 254, 33, 417, 497, 622, 286, 9, 967, 603, 78, 118, 304, 235, 985, 657, 741, 425, 995, 592, 844, 933, 99, 524, 418, 623, 529, 797, 342, 217, 580, 691, 772, 13, 390, 666, 87, 448, 505, 907, 765, 802, 484, 419, 669, 780, 96, 585, 796, 686, 302, 858, 388, 438, 893, 735, 360, 913, 902, 279, 720, 408, 287, 996, 507, 28, 416, 731, 928, 977, 547, 739, 788, 168, 331, 146, 664, 619, 723, 732, 102, 14, 424, 216, 575, 568, 93, 992, 272, 160, 389, 47, 647, 189, 988, 343, 991, 940, 358, 181, 611, 229, 265, 892, 422, 211, 443, 747, 736, 266, 652, 351, 612, 514, 876, 637, 329, 474, 68, 730, 825, 676, 778, 208, 956, 270, 398, 968, 268, 594, 288, 385, 866, 197, 428, 441, 672, 158, 618, 811, 363, 905, 462, 241, 226, 450, 309, 170, 822, 727, 333, 335, 92, 540, 202, 205, 115, 153, 569, 142, 290, 943, 394, 248, 228, 643, 415, 784, 579, 571, 291, 177, 711, 149, 130, 921, 922, 439, 951, 338, 769, 283, 308, 857, 253, 833, 490, 824, 518, 525, 131, 924, 27, 830, 915, 237, 694, 581, 609, 19, 152, 566, 465, 140, 81, 313, 969, 327, 6, 526, 135, 186, 656, 662, 155, 874, 648, 488, 199, 677, 952, 614, 722, 369, 682, 129, 478, 433, 809, 891, 717, 550, 748, 0, 323, 469, 151, 41, 299, 193, 487, 931, 634, 400, 799, 884, 405, 480, 76, 805, 926, 426, 312, 821, 178, 789, 449, 697, 853, 295, 48, 224, 397, 447, 946, 49, 382, 236, 867, 485, 349, 231, 227, 39, 38, 882, 210, 457, 222, 852, 665, 138, 455, 114, 204, 498, 511, 230, 509, 278, 365, 831, 412, 5, 816, 1, 324, 194, 464, 141, 420, 795, 839, 641, 10, 777, 15, 519, 829, 961, 109, 31, -5, 63, 421, 77, 430, 542, 452, 256, 355, 357, 704, 434, 459, 262, 132, 863, 468, 929, 716, 564, 890, 616, 855, 845, 548, 143, 145, 707, 787, 948, 11, 872, 61, 909, 762, 639, 786, 350, 136, 972, 75, 605, 354, 339, 305, 754, 755, 658, 40, 319, 620, 679, 984, 252, 477, 432, 684, 766, 280, 912, 949, 328, 834, 522, 310, 920, 546, 770, 214, 962, 678, 760, 916, -4, 401, 12, 957, 806, 791, 261, 277, 372, 17, 85, 982, 97, 125, 698, 399, 381, 655, 315, 182, 923, 886, 440, 223, 387, 173, 663, 588, 122, 113, 98, 803, 353, 668, 311, 587, 444, 636, 939, 429, 790, 718, 938, 738, 50, 362, 435, 813, 908, 650, 843, 959, 460, 849, 167, 384, 348, 467, 337, 356, 724, 516, 121, 880, 667, 779, 709, 986, 751, 51, 781, 659, 794, 653, 635, 553, 60, 322, 352, 696, 392, 250, 119, 431, 746, 164, 107, 563, 461, 532, 712, 391, 840, 380, 801, 574, 900, 576, 640, 378, 963, 601, 267, 207, 370, 225, 260, 500, 883, 159, 58, 166, 745, 179, 251, 271, 294, 257, 631, 895, 604, 828, 953, 520, 16, 818, 539, 491, 120, 875, 89, 692, 458, 552, 599, 861, 492, 74, 699, 55, 475, 345, 24, 700, 889, 937, 785, 758, 983 ]

expected output is 4

and my output is 1

here is my code https://jsbin.com/poduqayime/2/edit?html,js,console,output

i am not sure but i guess you are wrong here, you should go to codereview.stackexchange.com — Ilijanovic
– Ilijanovic, Commented Mar 19, 2020 at 8:43
@Ifaruki If the OP looks for a cleaner solution, then codereview suits best. If something doesn't work, putting on SO is on topic. — mighty_dev
– mighty_dev, Commented Mar 19, 2020 at 8:46
Does your algorithm handle the case where there are duplicate values in the array? — samgak
– samgak, Commented Mar 19, 2020 at 9:05

Shahzad Harim · Accepted Answer · 2020-03-19 09:39:38Z

// finding first missing +VE in javascript array
const firstMissingPositive = (arr=[]) => {for(i=1; ; i++) if(arr.indexOf(i) == -1) return i;}

// finding first missing +VE in javascript array
const firstMissingPositive = (arr=[]) => {for(i=1; ; i++) if(arr.indexOf(i) == -1) return i;}


let firstArr = [1,2,0]
console.log(`In firstArr missed : ${firstMissingPositive(firstArr)}`)

let secondArr = [3,4,-1,1]
console.log(`In secondArr missed : ${firstMissingPositive(secondArr)}`)

let thirdArr = [-8, -7, -6]
console.log(`In thirdArr missed : ${firstMissingPositive(thirdArr)}`)

let yourArr = [ 463, 127, 436, 72, 79, 301, 613, 898, 675, 960, 832, 486, 453, 274, 133, 721, 750, 538, 545, 112, 414, 817, 885, 812, 906, 577, 544, 101, 165, 45, 489, 503, 479, 293, 234, 427, 347, 851, 316, 827, 209, 578, 255, 56, 608, 914, 156, 537, 870, 567, 284, 240, 292, 111, 590, 713, 110, 768, 598, 879, 980, 660, 46, 320, 410, 869, 154, 970, 836, 423, 413, 501, 782, 403, 561, 117, 624, 638, 67, 646, 917, 379, 344, 543, 978, 506, 936, 947, 645, 633, 375, 706, 531, 470, 551, 632, 536, 642, 573, 705, 823, 897, 26, 476, 139, 496, 628, 91, 725, 570, 701, 244, 935, 126, 2, 560, 726, 20, 680, 7, 888, 183, 80, 804, 729, 583, 728, 515, 644, 774, 856, 192, 386, 25, 57, 471, 482, 174, 627, 757, 714, 203, 206, 847, 245, 336, 989, 326, 607, 95, 69, 71, 54, 975, 366, 591, 185, 964, 848, 84, 819, 737, 687, 215, 904, 651, 289, 134, 232, 341, 932, 64, 483, 128, 901, 808, 896, 941, 530, 195, 865, 903, 472, 508, 42, 971, 53, 86, 689, 925, 685, 934, 549, 841, 169, 317, 826, 600, 950, 90, 495, 219, 674, 814, 359, 556, 269, 187, 517, 541, 558, 8, 744, 958, 332, 163, 862, 218, 376, 23, 321, 346, 534, 864, 157, 285, 318, 200, 595, 810, 43, 32, 368, 753, 670, 887, 238, 1000, 513, 979, 499, 708, 473, 584, 981, 106, 695, 868, 881, 610, 273, 239, 190, 281, 373, 247, 364, 396, 837, 521, 871, 528, 617, 123, 894, 965, 108, 976, 451, 454, 673, 910, 681, 300, 702, 703, 307, 196, 535, 407, 763, 966, 945, 944, 65, 752, 776, 973, 554, 3, 998, 559, 35, -3, 147, 395, 761, 442, 586, 899, 191, 990, 606, 771, 393, 649, 987, 593, 877, 527, 201, 259, 150, 683, 263, 330, 21, 105, 406, 233, 303, 254, 33, 417, 497, 622, 286, 9, 967, 603, 78, 118, 304, 235, 985, 657, 741, 425, 995, 592, 844, 933, 99, 524, 418, 623, 529, 797, 342, 217, 580, 691, 772, 13, 390, 666, 87, 448, 505, 907, 765, 802, 484, 419, 669, 780, 96, 585, 796, 686, 302, 858, 388, 438, 893, 735, 360, 913, 902, 279, 720, 408, 287, 996, 507, 28, 416, 731, 928, 977, 547, 739, 788, 168, 331, 146, 664, 619, 723, 732, 102, 14, 424, 216, 575, 568, 93, 992, 272, 160, 389, 47, 647, 189, 988, 343, 991, 940, 358, 181, 611, 229, 265, 892, 422, 211, 443, 747, 736, 266, 652, 351, 612, 514, 876, 637, 329, 474, 68, 730, 825, 676, 778, 208, 956, 270, 398, 968, 268, 594, 288, 385, 866, 197, 428, 441, 672, 158, 618, 811, 363, 905, 462, 241, 226, 450, 309, 170, 822, 727, 333, 335, 92, 540, 202, 205, 115, 153, 569, 142, 290, 943, 394, 248, 228, 643, 415, 784, 579, 571, 291, 177, 711, 149, 130, 921, 922, 439, 951, 338, 769, 283, 308, 857, 253, 833, 490, 824, 518, 525, 131, 924, 27, 830, 915, 237, 694, 581, 609, 19, 152, 566, 465, 140, 81, 313, 969, 327, 6, 526, 135, 186, 656, 662, 155, 874, 648, 488, 199, 677, 952, 614, 722, 369, 682, 129, 478, 433, 809, 891, 717, 550, 748, 0, 323, 469, 151, 41, 299, 193, 487, 931, 634, 400, 799, 884, 405, 480, 76, 805, 926, 426, 312, 821, 178, 789, 449, 697, 853, 295, 48, 224, 397, 447, 946, 49, 382, 236, 867, 485, 349, 231, 227, 39, 38, 882, 210, 457, 222, 852, 665, 138, 455, 114, 204, 498, 511, 230, 509, 278, 365, 831, 412, 5, 816, 1, 324, 194, 464, 141, 420, 795, 839, 641, 10, 777, 15, 519, 829, 961, 109, 31, -5, 63, 421, 77, 430, 542, 452, 256, 355, 357, 704, 434, 459, 262, 132, 863, 468, 929, 716, 564, 890, 616, 855, 845, 548, 143, 145, 707, 787, 948, 11, 872, 61, 909, 762, 639, 786, 350, 136, 972, 75, 605, 354, 339, 305, 754, 755, 658, 40, 319, 620, 679, 984, 252, 477, 432, 684, 766, 280, 912, 949, 328, 834, 522, 310, 920, 546, 770, 214, 962, 678, 760, 916, -4, 401, 12, 957, 806, 791, 261, 277, 372, 17, 85, 982, 97, 125, 698, 399, 381, 655, 315, 182, 923, 886, 440, 223, 387, 173, 663, 588, 122, 113, 98, 803, 353, 668, 311, 587, 444, 636, 939, 429, 790, 718, 938, 738, 50, 362, 435, 813, 908, 650, 843, 959, 460, 849, 167, 384, 348, 467, 337, 356, 724, 516, 121, 880, 667, 779, 709, 986, 751, 51, 781, 659, 794, 653, 635, 553, 60, 322, 352, 696, 392, 250, 119, 431, 746, 164, 107, 563, 461, 532, 712, 391, 840, 380, 801, 574, 900, 576, 640, 378, 963, 601, 267, 207, 370, 225, 260, 500, 883, 159, 58, 166, 745, 179, 251, 271, 294, 257, 631, 895, 604, 828, 953, 520, 16, 818, 539, 491, 120, 875, 89, 692, 458, 552, 599, 861, 492, 74, 699, 55, 475, 345, 24, 700, 889, 937, 785, 758, 983 ]
console.log(`In yourArr missed : ${firstMissingPositive(yourArr)}`)

This does not answer where my function not working ? It gets avoidably slow for higher results.

norbekoff · Accepted Answer · 2022-01-19 04:55:51Z

3

Simple and easy solution using ES6 syntax Set

const firstMissingPositive = function(nums) {
    const set = new Set(nums);
    let min = 1;
    
    while(set.has(min)) {
        min++
    }
    return min
};

firstMissingPositive([1,2,0]) // returns 3

answered Jan 19, 2022 at 4:55

norbekoff

1,9141 gold badge13 silver badges25 bronze badges

1 Comment

Vladimir B. Over a year ago

I like that! Applied it on a simple task of mine, thank you pal.

mighty_dev · Accepted Answer · 2020-03-19 09:59:50Z

 if (arr[(arr[i]) - 1] > 0) {
     arr[(arr[i]) - 1] = -arr[(arr[i]) - 1]
 }

Above code creates the issue. Here, it's quite possible that the current arr[i] was already made negative by some other index. So, (arr[i]) - 1 would yield an even negative index. So, to solve this, you need to use absolute value using Math.abs().

You also have if(A[i] < 0){ in your first for loop. It's better to have it as if(A[i] <= 0){ as we don't care about non negative integer as well.

Your while loop has the condition if(arr[k]>0 || k >= arr.length){. It should rather be the other way round like if(k == arr.length || arr[k] > 0){

Overall, your code would look like below:

let firstMissingPositive = function(A) {
  let j = 0;
  for (let i = 0; i < A.length; i++) {
    if (A[i] <= 0) {
      let temp = A[j]
      A[j] = A[i]
      A[i] = temp;
      j++;
    }
  }

  let arr = A.slice(j);

  for (let i = 0; i < arr.length; i++) {
    if (arr[Math.abs(arr[i]) - 1] > 0) {
      arr[Math.abs(arr[i]) - 1] = -arr[Math.abs(arr[i]) - 1]
    }
  }

  let k = 0;
  while (true) {
    if (k == arr.length || arr[k] > 0) {
      break;
    }
    k++
  }
  return ++k
}

console.log(firstMissingPositive([463, 127, 436, 72, 79, 301, 613, 898, 675, 960, 832, 486, 453, 274, 133, 721, 750, 538, 545, 112, 414, 817, 885, 812, 906, 577, 544, 101, 165, 45, 489, 503, 479, 293, 234, 427, 347, 851, 316, 827, 209, 578, 255, 56, 608, 914, 156, 537, 870, 567, 284, 240, 292, 111, 590, 713, 110, 768, 598, 879, 980, 660, 46, 320, 410, 869, 154, 970, 836, 423, 413, 501, 782, 403, 561, 117, 624, 638, 67, 646, 917, 379, 344, 543, 978, 506, 936, 947, 645, 633, 375, 706, 531, 470, 551, 632, 536, 642, 573, 705, 823, 897, 26, 476, 139, 496, 628, 91, 725, 570, 701, 244, 935, 126, 2, 560, 726, 20, 680, 7, 888, 183, 80, 804, 729, 583, 728, 515, 644, 774, 856, 192, 386, 25, 57, 471, 482, 174, 627, 757, 714, 203, 206, 847, 245, 336, 989, 326, 607, 95, 69, 71, 54, 975, 366, 591, 185, 964, 848, 84, 819, 737, 687, 215, 904, 651, 289, 134, 232, 341, 932, 64, 483, 128, 901, 808, 896, 941, 530, 195, 865, 903, 472, 508, 42, 971, 53, 86, 689, 925, 685, 934, 549, 841, 169, 317, 826, 600, 950, 90, 495, 219, 674, 814, 359, 556, 269, 187, 517, 541, 558, 8, 744, 958, 332, 163, 862, 218, 376, 23, 321, 346, 534, 864, 157, 285, 318, 200, 595, 810, 43, 32, 368, 753, 670, 887, 238, 1000, 513, 979, 499, 708, 473, 584, 981, 106, 695, 868, 881, 610, 273, 239, 190, 281, 373, 247, 364, 396, 837, 521, 871, 528, 617, 123, 894, 965, 108, 976, 451, 454, 673, 910, 681, 300, 702, 703, 307, 196, 535, 407, 763, 966, 945, 944, 65, 752, 776, 973, 554, 3, 998, 559, 35, -3, 147, 395, 761, 442, 586, 899, 191, 990, 606, 771, 393, 649, 987, 593, 877, 527, 201, 259, 150, 683, 263, 330, 21, 105, 406, 233, 303, 254, 33, 417, 497, 622, 286, 9, 967, 603, 78, 118, 304, 235, 985, 657, 741, 425, 995, 592, 844, 933, 99, 524, 418, 623, 529, 797, 342, 217, 580, 691, 772, 13, 390, 666, 87, 448, 505, 907, 765, 802, 484, 419, 669, 780, 96, 585, 796, 686, 302, 858, 388, 438, 893, 735, 360, 913, 902, 279, 720, 408, 287, 996, 507, 28, 416, 731, 928, 977, 547, 739, 788, 168, 331, 146, 664, 619, 723, 732, 102, 14, 424, 216, 575, 568, 93, 992, 272, 160, 389, 47, 647, 189, 988, 343, 991, 940, 358, 181, 611, 229, 265, 892, 422, 211, 443, 747, 736, 266, 652, 351, 612, 514, 876, 637, 329, 474, 68, 730, 825, 676, 778, 208, 956, 270, 398, 968, 268, 594, 288, 385, 866, 197, 428, 441, 672, 158, 618, 811, 363, 905, 462, 241, 226, 450, 309, 170, 822, 727, 333, 335, 92, 540, 202, 205, 115, 153, 569, 142, 290, 943, 394, 248, 228, 643, 415, 784, 579, 571, 291, 177, 711, 149, 130, 921, 922, 439, 951, 338, 769, 283, 308, 857, 253, 833, 490, 824, 518, 525, 131, 924, 27, 830, 915, 237, 694, 581, 609, 19, 152, 566, 465, 140, 81, 313, 969, 327, 6, 526, 135, 186, 656, 662, 155, 874, 648, 488, 199, 677, 952, 614, 722, 369, 682, 129, 478, 433, 809, 891, 717, 550, 748, 0, 323, 469, 151, 41, 299, 193, 487, 931, 634, 400, 799, 884, 405, 480, 76, 805, 926, 426, 312, 821, 178, 789, 449, 697, 853, 295, 48, 224, 397, 447, 946, 49, 382, 236, 867, 485, 349, 231, 227, 39, 38, 882, 210, 457, 222, 852, 665, 138, 455, 114, 204, 498, 511, 230, 509, 278, 365, 831, 412, 5, 816, 1, 324, 194, 464, 141, 420, 795, 839, 641, 10, 777, 15, 519, 829, 961, 109, 31, -5, 63, 421, 77, 430, 542, 452, 256, 355, 357, 704, 434, 459, 262, 132, 863, 468, 929, 716, 564, 890, 616, 855, 845, 548, 143, 145, 707, 787, 948, 11, 872, 61, 909, 762, 639, 786, 350, 136, 972, 75, 605, 354, 339, 305, 754, 755, 658, 40, 319, 620, 679, 984, 252, 477, 432, 684, 766, 280, 912, 949, 328, 834, 522, 310, 920, 546, 770, 214, 962, 678, 760, 916, -4, 401, 12, 957, 806, 791, 261, 277, 372, 17, 85, 982, 97, 125, 698, 399, 381, 655, 315, 182, 923, 886, 440, 223, 387, 173, 663, 588, 122, 113, 98, 803, 353, 668, 311, 587, 444, 636, 939, 429, 790, 718, 938, 738, 50, 362, 435, 813, 908, 650, 843, 959, 460, 849, 167, 384, 348, 467, 337, 356, 724, 516, 121, 880, 667, 779, 709, 986, 751, 51, 781, 659, 794, 653, 635, 553, 60, 322, 352, 696, 392, 250, 119, 431, 746, 164, 107, 563, 461, 532, 712, 391, 840, 380, 801, 574, 900, 576, 640, 378, 963, 601, 267, 207, 370, 225, 260, 500, 883, 159, 58, 166, 745, 179, 251, 271, 294, 257, 631, 895, 604, 828, 953, 520, 16, 818, 539, 491, 120, 875, 89, 692, 458, 552, 599, 861, 492, 74, 699, 55, 475, 345, 24, 700, 889, 937, 785, 758, 983]));
console.log(firstMissingPositive([1, 2, 0]));
console.log(firstMissingPositive([3, 4, -1, 1]));
console.log(firstMissingPositive([-8, -7, -6]));
console.log(firstMissingPositive([-8]));

Mechanic · Accepted Answer · 2020-03-19 10:01:30Z

The logic here is to sort the array first; then if the number is positive and not equal to previous number + 1; then you'd found the missing number :)

function findTheMissingPossitiveInt(array) {
  let missing = 1;
  array.sort((m, n) => m - n);
  array.reduce((acc, cur, i, arr) => {
    if (cur > 0) {
      if (cur != acc + 1) {
        missing = acc + 1;
        //short-circuiting reduce execution
        arr.splice(1);
      }
    }
    return cur;
  }, 0);
  return missing;
}

const a = [  463,  127,  436,  72,  79,  301,  613,  898,  675,  960,  832,  486,  453,  274,  133,  721,  750,  538,  545,  112,  414,  817,  885,  812,  906,  577,  544,  101,  165,  45,  489,  503,  479,  293,  234,  427,  347,  851,  316,  827,  209,  578,  255,  56,  608,  914,  156,  537,  870,  567,  284,  240,  292,  111,  590,  713,  110,  768,  598,  879,  980,  660,  46,  320,  410,  869,  154,  970,  836,  423,  413,  501,  782,  403,  561,  117,  624,  638,  67,  646,  917,  379,  344,  543,  978,  506,  936,  947,  645,  633,  375,  706,  531,  470,  551,  632,  536,  642,  573,  705,  823,  897,  26,  476,  139,  496,  628,  91,  725,  570,  701,  244,  935,  126,  2,  560,  726,  20,  680,  7,  888,  183,  80,  804,  729,  583,  728,  515,  644,  774,  856,  192,  386,  25,  57,  471,  482,  174,  627,  757,  714,  203,  206,  847,  245,  336,  989,  326,  607,  95,  69,  71,  54,  975,  366,  591,  185,  964,  848,  84,  819,  737,  687,  215,  904,  651,  289,  134,  232,  341,  932,  64,  483,  128,  901,  808,  896,  941,  530,  195,  865,  903,  472,  508,  42,  971,  53,  86,  689,  925,  685,  934,  549,  841,  169,  317,  826,  600,  950,  90,  495,  219,  674,  814,  359,  556,  269,  187,  517,  541,  558,  8,  744,  958,  332,  163,  862,  218,  376,  23,  321,  346,  534,  864,  157,  285,  318,  200,  595,  810,  43,  32,  368,  753,  670,  887,  238,  1000,  513,  979,  499,  708,  473,  584,  981,  106,  695,  868,  881,  610,  273,  239,  190,  281,  373,  247,  364,  396,  837,  521,  871,  528,  617,  123,  894,  965,  108,  976,  451,  454,  673,  910,  681,  300,  702,  703,  307,  196,  535,  407,  763,  966,  945,  944,  65,  752,  776,  973,  554,  3,  998,  559,  35,  -3,  147,  395,  761,  442,  586,  899,  191,  990,  606,  771,  393,  649,  987,  593,  877,  527,  201,  259,  150,  683,  263,  330,  21,  105,  406,  233,  303,  254,  33,  417,  497,  622,  286,  9,  967,  603,  78,  118,  304,  235,  985,  657,  741,  425,  995,  592,  844,  933,  99,  524,  418,  623,  529,  797,  342,  217,  580,  691,  772,  13,  390,  666,  87,  448,  505,  907,  765,  802,  484,  419,  669,  780,  96,  585,  796,  686,  302,  858,  388,  438,  893,  735,  360,  913,  902,  279,  720,  408,  287,  996,  507,  28,  416,  731,  928,  977,  547,  739,  788,  168,  331,  146,  664,  619,  723,  732,  102,  14,  424,  216,  575,  568,  93,  992,  272,  160,  389,  47,  647,  189,  988,  343,  991,  940,  358,  181,  611,  229,  265,  892,  422,  211,  443,  747,  736,  266,  652,  351,  612,  514,  876,  637,  329,  474,  68,  730,  825,  676,  778,  208,  956,  270,  398,  968,  268,  594,  288,  385,  866,  197,  428,  441,  672,  158,  618,  811,  363,  905,  462,  241,  226,  450,  309,  170,  822,  727,  333,  335,  92,  540,  202,  205,  115,  153,  569,  142,  290,  943,  394,  248,  228,  643,  415,  784,  579,  571,  291,  177,  711,  149,  130,  921,  922,  439,  951,  338,  769,  283,  308,  857,  253,  833,  490,  824,  518,  525,  131,  924,  27,  830,  915,  237,  694,  581,  609,  19,  152,  566,  465,  140,  81,  313,  969,  327,  6,  526,  135,  186,  656,  662,  155,  874,  648,  488,  199,  677,  952,  614,  722,  369,  682,  129,  478,  433,  809,  891,  717,  550,  748,  0,  323,  469,  151,  41,  299,  193,  487,  931,  634,  400,  799,  884,  405,  480,  76,  805,  926,  426,  312,  821,  178,  789,  449,  697,  853,  295,  48,  224,  397,  447,  946,  49,  382,  236,  867,  485,  349,  231,  227,  39,  38,  882,  210,  457,  222,  852,  665,  138,  455,  114,  204,  498,  511,  230,  509,  278,  365,  831,  412,  5,  816,  1,  324,  194,  464,  141,  420,  795,  839,  641,  10,  777,  15,  519,  829,  961,  109,  31,  -5,  63,  421,  77,  430,  542,  452,  256,  355,  357,  704,  434,  459,  262,  132,  863,  468,  929,  716,  564,  890,  616,  855,  845,  548,  143,  145,  707,  787,  948,  11,  872,  61,  909,  762,  639,  786,  350,  136,  972,  75,  605,  354,  339,  305,  754,  755,  658,  40,  319,  620,  679,  984,  252,  477,  432,  684,  766,  280,  912,  949,  328,  834,  522,  310,  920,  546,  770,  214,  962,  678,  760,  916,  -4,  401,  12,  957,  806,  791,  261,  277,  372,  17,  85,  982,  97,  125,  698,  399,  381,  655,  315,  182,  923,  886,  440,  223,  387,  173,  663,  588,  122,  113,  98,  803,  353,  668,  311,  587,  444,  636,  939,  429,  790,  718,  938,  738,  50,  362,  435,  813,  908,  650,  843,  959,  460,  849,  167,  384,  348,  467,  337,  356,  724,  516,  121,  880,  667,  779,  709,  986,  751,  51,  781,  659,  794,  653,  635,  553,  60,  322,  352,  696,  392,  250,  119,  431,  746,  164,  107,  563,  461,  532,  712,  391,  840,  380,  801,  574,  900,  576,  640,  378,  963,  601,  267,  207,  370,  225,  260,  500,  883,  159,  58,  166,  745,  179,  251,  271,  294,  257,  631,  895,  604,  828,  953,  520,  16,  818,  539,  491,  120,  875,  89,  692,  458,  552,  599,  861,  492,  74,  699,  55,  475,  345,  24,  700,  889,  937,  785,  758,  983];
const b = [-1,-7,-8];
const c = [ -2, 0,1, 2 , 7];

console.log(findTheMissingPossitiveInt(a));
console.log(findTheMissingPossitiveInt(b));
console.log(findTheMissingPossitiveInt(c));

you can copy the array in the function body if mutation is a concern;

vantaku ramesh · Accepted Answer · 2022-02-24 05:44:57Z

0

Javascript

let firstMissingPositive = function(nums) {
    let len = nums.length;
    let tmp = 0;
    let i = 0;
    while (i < len) {

        tmp = nums[i];
if (tmp > 0 && tmp !== i + 1 && tmp !== nums[tmp - 1]) swap(nums, i,tmp - 1);

        else i++;
    }
    for (var j = 0; j < len; j++) {
        if (nums[j] !== j + 1) return j + 1;
    }
    return len + 1;
};

let swap = function (arr, i, j) {
    let tmp = arr[i];
    arr[i] = arr[j];
    arr[j] = tmp;
};

answered Feb 24, 2022 at 5:44

vantaku ramesh

394 bronze badges

1 Comment

Scott Sauyet Over a year ago

Welcome to StackOverflow. Please don't post code-only answers. Please edit to add some context and explanations.

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