Develop Reference

Splitting string into array based on first and last

I have this array :-
var a = [' DL1,C1,C5,C6','M4,DL3-7,B1-5']
And I want to split them like
[DL1,C1,C5,C6,M4,DL3,DL4,DL5,DL6,DL7,B1,B2,B3,B4,B5]
So that DL3-7 or DL3-DL7 this Split like this DL3,DL4,DL5,DL6,DL7
Reason why I am doing this, is because I want to block duplicate entry like DL3 should not come anywhere else, I am trying for loops to do this, just want to know if there is any simpler way to do it, and check for duplicacy afterwards.
Thanks

You have to break down your problems into three parts:
getting comma delimited values into different array items
resolving "DL3-7" to "DL3", "DL4"...
removing duplicates
Once you break down the problem, it is much easier to handle them one by one. The code is pretty readable, let me know if there is anything difficult to understand what's going on.
const a = ['DL1,C1,C5,C6', 'M4,DL3-7,B1-5']
//this will split all comma delimited values
const commaDelimit = a.map(item => item.split(',')).flat();
console.log("Separate values by comma: ")
console.log(commaDelimit);
//this will turn the ranges into individual items
//this does not account for if the number is bigger than 9.
//you can try doing this part yourself if you need to, should be a good learning exercise.
const resolveRange = commaDelimit.map(item => {
if (item.includes('-')) {
const pos = item.indexOf('-');
const beginning = Number(item.charAt(pos - 1));
const end = Number(item.charAt(pos + 1)) + 1;
const toReturn = [];
const prependString = item.substring(0, pos - 1);
for (let i = beginning; i < end; i++) {
toReturn.push(`${prependString}${i}`)
}
return toReturn;
}
return item;
}).flat();
console.log("Change 'DL3-7' to DL3, DL4 and so on: ")
console.log(resolveRange);
//this will get rid of duplicates
const uniques = [...new Set(resolveRange)];
console.log("Remove duplicates: ")
console.log(uniques);

Create an Array with that length, iterate and transform,
I've just wrote the most challenged part:
function splitRange(range) {
let a = range.split('-');
if (a.length < 2) return [range];
const baseString = (a[0].match(/[a-z A-Z]/g))?.join('');
const baseNumber = +((a[0].match(/\d+/))?.shift());
return Array.from({length: +a.pop().match(/\d+/) - baseNumber + 1}).map((_,i)=>`${baseString}${i+baseNumber}`);
}
const s='DL1,C1,C5,C6,M4,DL3-7,B1-5';
console.log(
s.split(',').map(item=>splitRange(item)).flat()
);

Basically, #cSharp has explained the concept of data transformation to the desired output.
Split by comma.
Work with regex to transform the range value and append it to the array. Regex pattern & test data
Distinct the array value.
var a = [' DL1,C1,C5,C6','M4,DL3-7,B1-5'];
var formatteds = a.reduce((previous, current) => {
var splits = current.trim().split(',');
var rangedSplits = splits.reduce((prev, cur) => {
var pattern = new RegExp(/([A-Z]*)(\d)-[A-Z]*(\d)/);
var match = pattern.exec(cur);
if (match) {
// Pattern 1: ['DL3-7', 'DL', '3', '7']
// Pattern 2: ['DL3-DL7', 'DL', '3', '7']
var startIndex = parseInt(match[2].toString());
var endIndex = parseInt(match[3].toString());
var arr = [];
for (let i = startIndex; i <= endIndex; i++) {
arr.push(match[1].toString() + i);
}
prev = prev.concat(arr);
} else {
prev = prev.concat([cur]);
}
return prev;
}, []);
previous = previous.concat(rangedSplits);
return previous;
}, []);
var result = formatteds.filter((x, i, array) => array.indexOf(x) === i);
console.log(result);

Find indices within a string where any combination of an array of words is found

Sample data:
String: "barfoofoobarthefoobarman"
Array of words: ["bar", "foo", "the"]
Output:
[6, 9, 12]
I was asked this question during an interview. Due to time constraint, I tried to find all the possible words that could be made out of the array of words (i. e. "barfoothe"), but was told that would not scale for large arrays. Was suggested to use a map data structure, but I think my solution doesn't scale either, and it's brute forced.
Here's the solution.
var solution = function(string, words) {
let output = [];
let wordsMap = new Map();
let wordsNumber = words.length;
let wordLength = words[0].length;
words.forEach((word) => {
if (!wordsMap.has(word))
wordsMap.set(word, 1);
else
wordsMap.set(word, wordsMap.get(word) + 1);
});
for (let i = 0; i <= string.length-(wordsNumber*wordLength); i+=wordLength) {
let tempMap = new Map(wordsMap);
let check = true;
let tempString = string.substring(i, i + wordsNumber*wordLength);
for (let j = 0; j <= tempString.length - wordLength; j += wordLength) {
let tempString2 = tempString.substring(j, j + wordLength);
if (tempMap.has(tempString2))
tempMap.set(tempString2, tempMap.get(tempString2) - 1);
}
for (let val of tempMap.values()){
if (val !== 0){
check = false
break;
}
}
if (check)
output.push(i)
}
console.log(output);
}
solution("barfoothefoobarman", ["foo", "bar"]);
Any suggestion for a smarter solution?

You could create a dynamic regular expression.
const words = ['foo', 'bar']
const rx = new RegExp(words.join('|'), 'g')
// todo escape special characters
Then search away.
const counts = words.map(it=>0) // [0,0]
// todo use map or object to track counts instead of array
while (m = rx.exec(inputString)) {
const index = words.indexOf(m[0])
counts[index]++
}

Thank you for your question. I think the question in the interview was less about the right solution and more about the right approach.
The trickiest part is actually just finding the word combinations. There are several approaches here. For me it's a clear case for recursion.
So my approach would be:
find all word combinations, except combinations with itself (for example: foofoo or barbar).
iterate through the word combinations and ask whether they are contained in the string.
extra: Sort SolutionArray
Done!
Note: I use indexOf() for point 2 but I think a regex match would make it even better because you find all possibilities of a word in a string and not just the first one like with indexOf. Would make sense for longer strings.
const arr = ["foo", "bar"];
const str = "barfoothefoobarman"
let res = [];
const combinations = (len, val, existing) => {
if (len == 0) {
res.push(val);
return;
}
for(let i=0; i<arr.length; i++) {
if(! existing[i]) {
existing[i] = true;
combinations(len-1, val + arr[i], existing);
existing[i] = false;
}
}
}
const buildCombinations = (arr = []) => {
for(let i = 0; i < arr.length; i++) {
combinations(arr.length - i, "", []);
}
};
buildCombinations(arr);
// exclude the base wordes from result array
newRes = res.filter((e) => {
if (! arr.includes(e)) {
return e;
}
})
console.log('all word combinations:', newRes);
// get the string position
const _positions = [];
newRes.forEach((w) => {
let res = str.indexOf(w);
if (res != -1 && ! _positions.includes(res)) {
_positions.push(res);
}
})
// sort array and use Float64Array to speed up
const positions = new Float64Array(_positions)
console.log('positions', positions.sort())

Javascript split strings in array on specific index

I have this array of strings.
const numbersArray = ['1000','10000','100000']
My goal is to split each one of them on specific index for example: output of 1000 should be 1,000 and etc...
Here is what i have right now:
const splitArrayHandler = (arr) =>{
for (let i = 0; i < arr.length; i++) {
let indexOfSymbol = Math.round(arr[i].length / 3)
return splitAtIndex(arr[i],indexOfSymbol)
}
}
const splitAtIndex = (value,index) => {
return value.substring(0,index) + ',' + value.substring(index)
}
splitArrayHandler(numbersArray)
The first function splitArrayHandler loops through my array,finds specific index of the symbol in the string and then function splitAtIndex does the rest of the hard work.
The problem is only first element of the string is passing to the splitAtIndexfunction and I dont understand why. any suggestions please?
const numbersArray = ['1000','10000','100000']
const splitArrayHandler = (arr) =>{
for (let i = 0; i < arr.length; i++) {
let indexOfSymbol = Math.round(arr[i].length / 3)
return splitAtIndex(arr[i],indexOfSymbol)
}
}
const splitAtIndex = (value,index) => {
return value.substring(0,index) + ',' + value.substring(index)
}
splitArrayHandler(numbersArray)

Use Intl.NumberFormat for the job. No need for string parsing / manipulating:
const numbersArray = ['1000', '10000', '100000', '654654686156', '1000.66', '10e14', '0xFFFF'];
const format = new Intl.NumberFormat('en-US').format;
const formattedNumbers = numbersArray.map(Number).map(format);
console.log(formattedNumbers);

You are breaking the loop by returning the splitAtIndex function. Create another array and push the results to it.
const splitArrayHandler = (arr) =>{
let arr2 = []
for (let i = 0; i < arr.length; i++) {
let indexOfSymbol = Math.round(arr[i].length / 3)
arr2.push(splitAtIndex(arr[i],indexOfSymbol))
}
return arr2
}

You might use regular expression and map function (though there is no real difference between map and hard coded loop)
const numbersArray = ['1000','10000','100000']
function addComa(x) {
return x.replace(/\B(?=(\d{3})+(?!\d))/g, ',')
}
const resolved = numbersArray.map(addComma)
console.log(resolved) // ['1,000','10,000','100,000']

Script to group elements where every character is same to each other

For input:
["abc","def","okg","fed","bca"]
expected output should be:
["abc","bca"],["def","fed"],["okg"]
here "abc", "bca" and "def", "fed" contains same character and "okg" there is no element which contains these character
const arr = ["abc", "def", "okg", "fed", "bca"];
let find = (arr) => {
let res = [];
for (let i = 0; i < arr.length; i++) {
for (let j = 1; j < arr.length; j++) {
if (arr[i].search(arr[j])) {
res.push(arr[j]);
}
}
}
return res;
}
console.log(find(arr))

A reduce will do the trick - it seems the shortest code here (apart from the one using lodash)
const arr = ["abc", "def", "okg", "fed", "bca"],
res = Object.values(arr.reduce((acc, ele) => {
const key = ele.split("").sort();
(acc[key] = acc[key] || []).push(ele)
return acc
}, {}))
console.log(res)

.search returns a number indicating the index of where the match was found. Check that the result isn't -1 instead of checking that the result is truthy. But...
.search isn't the right tool here anyway, because it won't find different combinations of the same character. You need a different approach. One way would be to create an object whose keys are the characters found, and the values are the number of occurrences, then use a sorted representation of that object as a key. For example, have both abc and bca turn into something like:
a,1-b,1-c,1
Iterate through the input array, generating a key for each string, and putting the string on an object with that key. At the end, take the object's values.
const strToKey = (str) => {
const grouped = {};
for (const char of str) {
grouped[char] = (grouped[char] || 0) + 1;
}
return Object.entries(grouped)
.sort((a, b) => a[0].localeCompare(b[0]))
.join('-');
};
let find = (arr) => {
const grouped = {};
for (const str of arr) {
const key = strToKey(str);
grouped[key] ??= [];
grouped[key].push(str);
}
return Object.values(grouped);
}
console.log(find(["abc", "def", "okg", "fed", "bca"]));
Another option, when creating the keys, instead of sorting the object afterwards, you could sort the string first:
const strToKey = (str) => {
const grouped = {};
for (const char of [...str].sort()) {
grouped[char] = (grouped[char] || 0) + 1;
}
return Object.entries(grouped).join('-');
};
let find = (arr) => {
const grouped = {};
for (const str of arr) {
const key = strToKey(str);
grouped[key] ??= [];
grouped[key].push(str);
}
return Object.values(grouped);
}
console.log(find(["abc", "def", "okg", "fed", "bca"]));

const input = ["abc","def","okg","fed","bca"]
function getSortedString (str) {
return [...str].sort().join('');
};
function groupBy(input) {
const grouped = [];
while(input.length) {
const nextInput = [];
const first = input[0];
const matched = [first];
for (let i = 1; i < input.length; i++) {
if(getSortedString(first) === getSortedString(input[i])) {
matched.push(input[i])
} else {
nextInput.push(input[i])
}
}
input = nextInput;
grouped.push(matched);
}
console.log(grouped);
}
groupBy(input);

Using Object.values and groupBy (from lodash), you can get a straightforward solution:
You group your array elements by their "sorted" form and then use Object.values to get the output array.
const arr = ["abc", "def", "okg", "fed", "bca"];
const sortString = (str) => str.split("").sort().join("")
const result = Object.values(_.groupBy(arr, sortString));
console.log(result);
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.21/lodash.min.js"></script>

Converting Tree Like File Directory to a JSON object

I'm trying to convert a file directory response into a JSON object.
Here's a copy of the response from the file directory function.
[ 'C:/Users/Freddy/System/storage/Objects/Users/1',
'C:/Users/Freddy/System/storage/Objects/Users/1/email',
'C:/Users/Freddy/System/storage/Objects/Users/1/email/FreddyMcGee#Gmail.com',
'C:/Users/Freddy/System/storage/Objects/Users/1/etc',
'C:/Users/Freddy/System/storage/Objects/Users/1/etc/etc',
'C:/Users/Freddy/System/storage/Objects/Users/1/password',
'C:/Users/Freddy/System/storage/Objects/Users/1/password/123123123213',
'C:/Users/Freddy/System/storage/Objects/Users/1/username',
'C:/Users/Freddy/System/storage/Objects/Users/1/username/Freddy1337' ]
And this is the ouput that i'm trying/aiming to achieve:
1 : {
email: "FreddyMcGee#Gmail.com",
etc: etc,
password: "12313123",
username: "Freddy1337"
}
Simply the shortest path in the directory is the start of JSON object. All previous 'folder directories' are clipped.
I've attempted myself to write a function that does so, however I had some trouble since the folder 'Users' appears twice. Also the function doesn't traverse the nodes properly, it just cuts it at set sections and glues them together. It's very horrible, i'm a bit ashamed.
function TreeToJson(directory, cutAfter){
for (var i = directory.length - 1; i >= 0; i--) {
directory[i] = directory[i].substr(directory[i].indexOf(cutAfter) + cutAfter.length, directory[i].length - 1);
directory[i] = directory[i].split("/");
directory[i].shift();
};
jsonA = {}; jsonB = {}; jsonC = {};
for (var i = 0; i < directory.length; i++) {
if(directory[i][2] != undefined){
jsonB[directory[i][2]] = directory[i][3]
}
};
jsonC[Number([directory[0][1]])] = jsonB;
jsonA[directory[0][0]] = jsonC;
return jsonA;
}
TreeToJson(files, 'Objects');
If someone can show me a better approach into converting a 'Tree View Model' into a 'JSON Object' i'd appreciate it. I'm curious on the approaches other developers would take, and also what the most simplest solution would be.

A very common operation is extracting the part of the string after the last slash, so I'd make a regular expression function for that. Identify the starting directory name from the first element in the array, and then use a simple for loop to iterate through the rest of the array, two-by-two, extracting the keys and values:
const input = [
'C:/Users/Freddy/System/storage/Objects/Users/1',
'C:/Users/Freddy/System/storage/Objects/Users/1/email',
'C:/Users/Freddy/System/storage/Objects/Users/1/email/FreddyMcGee#Gmail.com',
'C:/Users/Freddy/System/storage/Objects/Users/1/etc',
'C:/Users/Freddy/System/storage/Objects/Users/1/etc/etc',
'C:/Users/Freddy/System/storage/Objects/Users/1/password',
'C:/Users/Freddy/System/storage/Objects/Users/1/password/123123123213',
'C:/Users/Freddy/System/storage/Objects/Users/1/username',
'C:/Users/Freddy/System/storage/Objects/Users/1/username/Freddy1337'
];
const lastPart = str => str.match(/\/([^\/]+)$/)[1];
const [baseDirectory, ...keysVals] = input;
const dirName = lastPart(baseDirectory);
const dirObj = {};
for (let i = 0; i < keysVals.length; i += 2) {
const key = lastPart(keysVals[i]);
const val = lastPart(keysVals[i + 1]);
dirObj[key] = val;
}
const output = { [dirName]: dirObj };
console.log(output);

you can split by 'Users' and .reduce() the resulting array :
const data = ['C:/Users/Freddy/System/storage/Objects/Users/1',
'C:/Users/Freddy/System/storage/Objects/Users/1/email',
'C:/Users/Freddy/System/storage/Objects/Users/1/email/FreddyMcGee#Gmail.com',
'C:/Users/Freddy/System/storage/Objects/Users/1/etc',
'C:/Users/Freddy/System/storage/Objects/Users/1/etc/etc',
'C:/Users/Freddy/System/storage/Objects/Users/1/password',
'C:/Users/Freddy/System/storage/Objects/Users/1/password/123123123213',
'C:/Users/Freddy/System/storage/Objects/Users/1/username',
'C:/Users/Freddy/System/storage/Objects/Users/1/username/Freddy1337'
];
const objects = data
.map(e => {
return e.split('Users')[2];
})
.reduce((all, curr) => {
let elems = curr.split('/');
all[elems[1]] = all[elems[1]] || {};
if ([elems[2]] && elems[3]) {
Object.assign(all[elems[1]], {
[elems[2]]: elems[3]
})
}
// elems[1] is : 1
// elems[2] is the key ( username, password .. )
// elems[3] is the value ( Freddy1337 ... )
return all;
}, {})
console.log(objects)
EDIT : same code above wrapped in a function :
const tree = ['C:/Users/Freddy/System/storage/Objects/Users/1',
'C:/Users/Freddy/System/storage/Objects/Users/1/email',
'C:/Users/Freddy/System/storage/Objects/Users/1/email/FreddyMcGee#Gmail.com',
'C:/Users/Freddy/System/storage/Objects/Users/1/etc',
'C:/Users/Freddy/System/storage/Objects/Users/1/etc/etc',
'C:/Users/Freddy/System/storage/Objects/Users/1/password',
'C:/Users/Freddy/System/storage/Objects/Users/1/password/123123123213',
'C:/Users/Freddy/System/storage/Objects/Users/1/username',
'C:/Users/Freddy/System/storage/Objects/Users/1/username/Freddy1337'
];
function TreeToJson(data, cutAfter){
const objects = data
.map(e => {
return e.split(cutAfter)[1];
})
.reduce((all, curr) => {
let elems = curr.split('/');
all[elems[2]] = all[elems[2]] || {};
if([elems[3]] && elems[4]){
Object.assign(all[elems[2]], {
[elems[3]] : elems[4]
})
}
return all;
}, {})
return objects;
}
console.log(TreeToJson(tree, 'Objects'))