Javascript Interview Question Array Get all sub sets

Introduction

A subset is a set of which all the elements are contained in another set.

Given an array, return the array containing all unique subsets

Example: 

subsets(['a', 'b', 'c']) 
should return /*ww  w .j  a  v a 2 s  .co m*/
[[], 
 ['a'], 
 ['b'], 
 ['a', 'b'], 
 ['c'], 
 ['a', 'c'], 
 ['b', 'c'], 
 ['a', 'b', 'c']
]


function subsets(array) {
}
/*  Do not edit below this line */

var line = '****************************************************************';
var passed = 0;//from   w  w  w. j  a v a2  s  .com
var failed = 0;

console.log(line);
console.log('subsets UNIT TESTS');
console.log(line);

if (JSON.stringify(subsets([])) === JSON.stringify([[]])) {
    console.log("Test 1 pass, subsets([]) returns [[]]");
    passed += 1;
} else {
    console.log("Test 1 failed, subsets([]) should return [[]]");
    console.log(subsets([]));
    failed += 1;
}

var subsetsResult = subsets(['a', 'b', 'c']);
if (JSON.stringify(subsetsResult.sort()) === JSON.stringify([[], ['a'], ['b'], ['a', 'b'], ['c'], ['a', 'c'], ['b', 'c'], ['a', 'b', 'c']].sort())) {
    console.log("Test 2 pass, subsets(['a', 'b', 'c']) returns all the elements in [[], ['a'], ['b'], ['a', 'b'], ['c'], ['a', 'c'], ['b', 'c'], ['a', 'b', 'c']]");
    passed += 1;
} else {
    console.log("Test 2 failed, subsets(['a', 'b', 'c']) should return all the elements in [[], ['a'], ['b'], ['a', 'b'], ['c'], ['a', 'c'], ['b', 'c'], ['a', 'b', 'c']]");
    failed += 1;
}

subsetsResult = subsets(['a', 'b', 'c', 'd']);
if (JSON.stringify(subsetsResult.sort()) === JSON.stringify([[], ['a'], ['b'], ['a', 'b'], ['c'], ['a', 'c'], ['b', 'c'], ['a', 'b', 'c'], ['d'], ['a', 'd'], ['b', 'd'], ['a', 'b', 'd'], ['c', 'd'], ['a', 'c', 'd'], ['b', 'c', 'd'], ['a', 'b', 'c', 'd']].sort())) {
    console.log("Test 3 pass, subsets(['a', 'b', 'c', 'd']) returns [[], ['a'], ['b'], ['a', 'b'], ['c'], ['a', 'c'], ['b', 'c'], ['a', 'b', 'c'], ['d'], ['a', 'd'], ['b', 'd'], ['a', 'b', 'd'], ['c', 'd'], ['a', 'c', 'd'], ['b', 'c', 'd'], ['a', 'b', 'c', 'd']");
    passed += 1;
} else {
    console.log("Test 3 failed, subsets(['a', 'b', 'c', 'd']) should return [[], ['a'], ['b'], ['a', 'b'], ['c'], ['a', 'c'], ['b', 'c'], ['a', 'b', 'c'], ['d'], ['a', 'd'], ['b', 'd'], ['a', 'b', 'd'], ['c', 'd'], ['a', 'c', 'd'], ['b', 'c', 'd'], ['a', 'b', 'c', 'd']");
    failed += 1;
}

console.log(line);
console.log('TOTAL TESTS PASSED: ' + passed );
console.log('TOTAL TESTS FAILED: ' + failed );
console.log(line);





function subsets(array) {
    var result = [[]];

    for (var i = 0; i < array.length; i += 1) {
        var resultLength = result.length;
        var newElement = array[i];

        for (var j = 0; j < resultLength; j += 1) {
            var newSubset = result[j].concat([newElement]);
            result.push(newSubset);
        }
    }

    return result;
}

// Subsets problem is a great example where recursion simplifies the logic
function subsets2(array) {
    if (array.length === 0) return [[]];

    var newElement = array[0];
    var subSubsets = subsets(array.slice(1));
    var newSubsets = subSubsets.map(subSubset => [newElement].concat(subSubset) );

    return subSubsets.concat(newSubsets);
}






/*  Do not edit below this line */

var line = '****************************************************************';
var passed = 0;
var failed = 0;

console.log(line);
console.log('subsets UNIT TESTS');
console.log(line);

if (JSON.stringify(subsets([])) === JSON.stringify([[]])) {
    console.log("Test 1 pass, subsets([]) returns [[]]");
    passed += 1;
} else {
    console.log("Test 1 failed, subsets([]) should return [[]]");
    console.log(subsets([]));
    failed += 1;
}

var subsetsResult = subsets(['a', 'b', 'c']);
if (JSON.stringify(subsetsResult.sort()) === JSON.stringify([[], ['a'], ['b'], ['a', 'b'], ['c'], ['a', 'c'], ['b', 'c'], ['a', 'b', 'c']].sort())) {
    console.log("Test 2 pass, subsets(['a', 'b', 'c']) returns all the elements in [[], ['a'], ['b'], ['a', 'b'], ['c'], ['a', 'c'], ['b', 'c'], ['a', 'b', 'c']]");
    passed += 1;
} else {
    console.log("Test 2 failed, subsets(['a', 'b', 'c']) should return all the elements in [[], ['a'], ['b'], ['a', 'b'], ['c'], ['a', 'c'], ['b', 'c'], ['a', 'b', 'c']]");
    failed += 1;
}

subsetsResult = subsets(['a', 'b', 'c', 'd']);
if (JSON.stringify(subsetsResult.sort()) === JSON.stringify([[], ['a'], ['b'], ['a', 'b'], ['c'], ['a', 'c'], ['b', 'c'], ['a', 'b', 'c'], ['d'], ['a', 'd'], ['b', 'd'], ['a', 'b', 'd'], ['c', 'd'], ['a', 'c', 'd'], ['b', 'c', 'd'], ['a', 'b', 'c', 'd']].sort())) {
    console.log("Test 3 pass, subsets(['a', 'b', 'c', 'd']) returns [[], ['a'], ['b'], ['a', 'b'], ['c'], ['a', 'c'], ['b', 'c'], ['a', 'b', 'c'], ['d'], ['a', 'd'], ['b', 'd'], ['a', 'b', 'd'], ['c', 'd'], ['a', 'c', 'd'], ['b', 'c', 'd'], ['a', 'b', 'c', 'd']");
    passed += 1;
} else {
    console.log("Test 3 failed, subsets(['a', 'b', 'c', 'd']) should return [[], ['a'], ['b'], ['a', 'b'], ['c'], ['a', 'c'], ['b', 'c'], ['a', 'b', 'c'], ['d'], ['a', 'd'], ['b', 'd'], ['a', 'b', 'd'], ['c', 'd'], ['a', 'c', 'd'], ['b', 'c', 'd'], ['a', 'b', 'c', 'd']");
    failed += 1;
}

console.log(line);
console.log('TOTAL TESTS PASSED: ' + passed );
console.log('TOTAL TESTS FAILED: ' + failed );
console.log(line);



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