We are required to write a JavaScript function that takes in an array of Integers that might contain some repeating values. Our function should find out the number of pairs of identical integers we can extract out of the array.
For example −
If the input array is −
const arr = [1, 5, 2, 1, 6, 2, 2, 9];
Then the output should be −
const output = 2;
because the desired pairs are 1, 1 and 2, 2
Example
The code for this will be −
const arr = [1, 5, 2, 1, 6, 2, 2, 9];
const countPairs = (arr = []) => {
const { length } = arr;
let count = 0;
// making a shallow copy so that the original array remains unaltered
const copy = arr.slice();
copy.sort((a, b) => a - b);
for(let i = 0; i < length; i++){
if(copy[i] === copy[i + 1]){
i++;
count++;
};
};
return count;
};
console.log(countPairs(arr));Output
And the output in the console will be −
2