How do I find a pair in an array?-CodePudding

I was wondering how do I make a function that would return true if there's a pair in an array of 6 numbers? I tried to use this (the sortThingfunction is sorting the numbers array)

let arr = [];

this.sortThing();
for (let i = 0; i < numbers.length; i  )
{
    for (let j = i   1; j < numbers.length; j  )
    {
        while (arr.length < 5) 
        {
            if (arr.push(numbers[i] == numbers[j]))
                return numbers;
            i  ;
        }
    }
}

CodePudding user response：

I suggest sorting the array ascending, then walking down the array once looking for any array element to repeat:

var numbers = [1, 5, 3, 7, 3];
numbers.sort((a, b) => a - b);
var pair = false;
var last = numbers[0];
for (var i=1; i < numbers.length;   i) {
    if (last == numbers[i]) {
        pair = true;
        break;
    }

    last = numbers[i];
}

if (pair) {
    console.log("Array has a pair number: "   last);
}
else {
    console.log("No pair was found in the array.");
}

CodePudding user response：

const hasDuplicates = (arr) => {
  const set = new Set(arr);
  return set.size !== arr.length;
}
console.log(hasDuplicates([1, 2, 3, 4, 5, 4, 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]))

CodePudding user response：

var numbers = [1,2,3,4]
var firstelement
var checker = false

while (numbers.length>0) {
  firstelement = numbers[0]
  numbers.shift()
  if(numbers.indexOf(firstelement) !== -1){
    checker = true
    break
  }
}
console.log(checker)

CodePudding user response：

with a 6 digit array is easy to find duplicated using XOR

const numbers = [1, 5, 3, 7, 3];
let y;
for(const x of numbers){
  y ^= x
}
console.log(y)