Answers for "how to find duplicate elements in an array"

4

java array check duplicates

duplicates = false;

for(i = 0; i < zipcodeList.length; i++) {
	for(j = i + 1; k < zipcodeList.length; j++) {
  		if(j != i && zipcodeList[j] == zipcodeList[i]) {
   	  		duplicates = true;
		}
	}
}
Posted by: Guest on February-15-2020
1

find duplicates in array

function findDuplicates(arr) {
	const duplicates = new Set()
  
  return arr.filter(item => {
  	if (duplicates.has(item)) {
    	return true
    }
    duplicates.add(item)
    return false
  })
}
Posted by: Guest on August-06-2021
2

javascript find duplicate in array

// JavaScript - finds if there is duplicate in an array. 
// Returns True or False.

const isThereADuplicate = function(arrayOfNumbers) {
    // Create an empty associative array or hash. 
    // This is preferred,
    let counts = {};
    // // but this also works. Comment in below and comment out above if you want to try.
    // let counts = [];

    for(var i = 0; i <= arrayOfNumbers.length; i++) {
        // As the arrayOfNumbers is being iterated through,
        // the counts hash is being populated.
        // Each value in the array becomes a key in the hash. 
        // The value assignment of 1, is there to complete the hash structure.
        // Once the key exists, meaning there is a duplicate, return true.
        // If there are no duplicates, the if block completes and returns false.
        if(counts[arrayOfNumbers[i]] === undefined) {
            counts[arrayOfNumbers[i]] = 1;
        } else {
            return true;
        }
    }
    return false;
}
Posted by: Guest on April-09-2020
0

Find duplicate or repeat elements in js array

function findUniq(arr) {
  return arr.find(n => arr.indexOf(n) === arr.lastIndexOf(n));
}

console.log(findUniq([ 0, 1, 0 ]))
console.log(findUniq([ 1, 1, 1, 2, 1, 1 ]))
console.log(findUniq([ 3, 10, 3, 3, 3 ]))
console.log(findUniq([ 7, 7, 7, 20, 7, 7, 7 ]))
Posted by: Guest on October-11-2021
0

find duplicate values in array javascript

const findDuplicates = (arr) => {
  let sorted_arr = arr.slice().sort(); // You can define the comparing function here. 
  // JS by default uses a crappy string compare.
  // (we use slice to clone the array so the
  // original array won't be modified)
  let results = [];
  for (let i = 0; i < sorted_arr.length - 1; i++) {
    if (sorted_arr[i + 1] == sorted_arr[i]) {
      results.push(sorted_arr[i]);
    }
  }
  return results;
}

let duplicatedArray = [9, 4, 111, 2, 3, 9, 4, 5, 7];
console.log(`The duplicates in ${duplicatedArray} are ${findDuplicates(duplicatedArray)}`);
Posted by: Guest on January-09-2021
0

Find duplicate or repeat elements in js array

const a = [4,3,6,3,4,3]

function count_duplicate(a){
 let counts = {}

 for(let i =0; i < a.length; i++){ 
     if (counts[a[i]]){
     counts[a[i]] += 1
     } else {
     counts[a[i]] = 1
     }
    }  
    for (let prop in counts){
        if (counts[prop] >= 2){
            console.log(prop + " counted: " + counts[prop] + " times.")
        }
    }
  console.log(counts)
}

count_duplicate(a)
Posted by: Guest on October-11-2021

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