how to count duplicate elements in an array

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amir zivyeh answered on June 8, 2021 Popularity 9/10 Helpfulness 4/10

answer how to count duplicate elements in an array

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related Find / Display duplicate numbers in array

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how to count duplicate elements in an array

Comment

const myArray = ['a', 'b', 'c', 'c', 'b', 'd'];
const elementCounts = {};
myArray.forEach(element => {
  elementCounts[element] = (elementCounts[element] || 0) + 1;
});
console.log(elementCounts);
//output
/*{
  a: 1,
  b: 2,
  c: 2,
  d: 1
}*/

Popularity 9/10 Helpfulness 4/10 Language typescript

Source: www.jsowl.com

Tags: count elements typescript

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Contributed on Sep 09 2023

amir zivyeh

0 Answers Avg Quality 2/10

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how to find duplicates in an array

Comment

const numbers = [1, 2, 3, 2, 4, 5, 5, 6];

const set = new Set(numbers);

const duplicates = numbers.filter(item => {
    if (set.has(item)) {
        set.delete(item);
    } else {
        return item;
    }
});

console.log(duplicates);
// [ 2, 5 ]

Popularity 10/10 Helpfulness 4/10 Language javascript

Source: attacomsian.com

Tags: find

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Contributed on Jul 23 2022

Samuel Abusa Kennedy

0 Answers Avg Quality 2/10

duplicate array values

Comment

public class Main {
public static void main(String[] args) {
  int[] arr1 = {1,2,3,3,4};
  for (int i = 0; i < arr1.length-1 ; i++) {
    for (int j = 0; j < arr1.length; j++) {
      if (arr1[i]==arr1[j] && (j != i)){
      System.out.println("array's duplicate number: " +
      arr1[j]);
      	}
      }
    }
	}
}

Popularity 9/10 Helpfulness 2/10 Language java

Source: Grepper

Tags: java

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Contributed on Oct 21 2022

Breakable Boar

0 Answers Avg Quality 2/10

array iteration + find duplicates

Comment

function lonelyinteger(a: number[]): number {
   for (let item of a) {
        const items = a.filter(el => item === el)
        if (items.length === 1) {
            return item
        }
    }
}



const a:number[] = [1,2,3,4,3,2,1]

const result:number = lonelyinteger(a);
console.log(result)

Popularity 8/10 Helpfulness 2/10 Language typescript

Source: Grepper

Tags: find iteration iter

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Contributed on Nov 13 2022

Quaint Quelea

0 Answers Avg Quality 2/10

Find / Display duplicate numbers in array

Comment

var input = [1, 2, 5, 5, 3, 1, 3, 1];
    var duplicates = input.reduce(function(acc, el, i, arr) {
    if (arr.indexOf(el) !== i && acc.indexOf(el) < 0) acc.push(el); return acc;
    }, []);
    console.log(duplicates);

Popularity 9/10 Helpfulness 2/10 Language javascript

Source: Grepper

Tags: display

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Contributed on Aug 17 2022

sri teja

0 Answers Avg Quality 2/10

count of duplicate number in array

Comment

def FirstOccurrence ( array, n ) :
    
    beg = 0
    end = len(array) - 1

    while (beg <= end) :

        mid = int (beg + (end-beg)/2)

        if (array[mid] == n) :
            if (mid-1 >= 0 and array[mid-1] == n) :
               end = mid-1
               continue

            return mid 

        elif (array[mid] < n) :
            beg = mid + 1 
        else :
            end = mid - 1 

    return -1  

def LastOccurrence (array, n) :
    
    beg = 0
    end = len(array)-1

    while (beg <= end) :

        mid = int(beg + (end-beg)/2)

        if (array[mid] == n) :
            if (mid+1 < len(array) and array[mid+1] == n) :
               beg = mid + 1 
               continue
            return mid 

        elif (array[mid] < n) :
            beg = mid + 1 
        else :
            end = mid - 1

    return -1; 

array = [ 1, 2, 3, 9, 9, 9, 9, 10, 10, 12, 13 ]
n = int (input("Enter the number : "))

first_index = FirstOccurrence (array, n)
last_index  = LastOccurrence (array, n)

if (first_index == -1 or last_index == - 1) :
    print("Element does not exist")
else :
    print("First occurrence of " + str(n) + " is at index : " + str(first_index))
    print("Last occurrence of " + str(n) + " is at index : " + str(last_index))
    print("Total count : "+ str(last_index - first_index + 1))

Popularity 10/10 Helpfulness 1/10 Language whatever

Source: www.algotree.org

Tags: count coun

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Contributed on Jun 08 2021

Open Oyster

0 Answers Avg Quality 2/10

how to count duplicate elements in an array

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how to count duplicate elements in an array

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how to find duplicates in an array

duplicate array values

array iteration + find duplicates

Find / Display duplicate numbers in array

count of duplicate number in array

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