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Check if some elements of array are equal JavaScript
We have an array of numbers that have got some redundant entries, our job is to write a function that takes in the array and groups all the identical entries into one subarray and returns the new array thus formed.
For example −
//If the input array is: const arr = [1, 3, 3, 1]; //then the output should be: const output = [[1, 1], [3, 3]];
We will use a HashMap to keep a track of the elements already occurred and iterate over the array using a for loop, the code for this will be −
Example
const arr = [1, 3, 3, 1];
const groupArray = arr => {
const map = {};
const group = [];
for(let i = 0; i < arr.length; i++){
if(typeof map[arr[i]] === 'number'){
group[map[arr[i]]].push(arr[i]);
} else {
//the push method returns the new length of array
//and the index of newly pushed element is length-1
map[arr[i]] = group.push([arr[i]])-1;
}
};
return group;
}
console.log(groupArray(arr));Output
The output in the console will be −
[ [ 1, 1 ], [ 3, 3 ] ]
Updated on 25-Aug-2020 07:13:13
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