How to generate all subarrays in javascript in 2022?

Hello Readers,

Interviewers like to ask questions about the subarrays as it gives a clear indication of the logical thinking and aptitude of a candidate.

Considering the above, we are going to start a new tag MCAIQ (most commonly asked interview questions) on weekendtutorial that will contain the most frequently asked questions in the interview. This will be your single stop for all such questions and interview preparations.

we will see how to generate all the subarrays of an array in javascript using iterative and recursive ways both.

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Generate all subarrays using iteration

Problem Statement

Given an array, generate all the possible subarrays of the given array using an iterative way.

Input : [1, 2, 3]

Output: [1], [1, 2], [1, 2, 3], [2], [2, 3], [3]

Input: [1, 2]

Output: [1], [1, 2], [2]

Implementation

	function generateAllSubArrays(arr) {
	const n = arr.length;
	for (let i = 0; i < n; i++) {
	for (let j = i; j < n; j++) {
	// we have index i and j of the subarray, let's print it
	let ans = [];
	for (let k = i; k <= j; k++) {
	ans.push(arr[k]);
	}
	console.log(ans);
	}
	}
	}
	console.log('all subarrays for [1,2,3]');
	generateAllSubArrays([1,2,3]);
	console.log('all subarrays for [1,2]');
	generateAllSubArrays([1,2]);

view raw iterative.js hosted with ❤ by GitHub

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Generate all subarrays using recursion

Implementation

	function generateAllSubArrays(arr, n, start, end) {
	if (start >= n && end >= n) return;
	if (end >= n) {
	generateAllSubArrays(arr, n, start+1, start+1);
	} else {
	let ans = [];
	for (let k = start; k <= end; k++) {
	ans.push(arr[k]);
	};
	console.log(ans);
	generateAllSubArrays(arr, n, start, end+1);
	}
	}
	console.log('all subarrays for [1,2,3]');
	generateAllSubArrays([1,2,3], 3, 0, 0);
	console.log('all subarrays for [1,2]');
	generateAllSubArrays([1,2], 2, 0, 0);

view raw recursion.js hosted with ❤ by GitHub

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