Newer to coding and javascript and I am trying a codewars challenge. I setup an array to repeat a letter at certain indexes of my newArray based on a loop. For example if input was: cwAt expected output should be: C-Ww-Aaa-Tttt.
Been stuck on this for several hours (and have slept on it). I get error code:
newArray.join is not a function
when I try to run this and not sure what I can do to fix this problem. I feel its something simple and I just need to learn why this is happening.
function accum(s) {
let mumble = s.split('');
for (i = 0; i < mumble.length; i++) {
let newArray = [mumble[i].toUpperCase(), ''];
for (j = i; j > 0; j--) {
newArray = newArray.push(mumble[i]);
};
// Merge the new array into a string and set it at the mumble index required
mumble[i] = newArray.join('');
};
//Return new mumble with - as spaces between elements
return mumble.join('-');
}
console.log(accum('cwAt'));
Change newArray = newArray.push(mumble[i]); to newArray.push(mumble[i]);
push returns new length of the array.
You are storing a number in newArray. Try replace the 4 line with:
let newArray[i] = [mumble[i].toUpperCase(), ''];
and the 5 line :
for (j = 0; j < 0; j++) {
and the 6:
newArray[j] = newArray.push(mumble[i]);
Related
Example :
Input: nums = [0,0,1,1,1,2,2,3,3,4]
Output: 5, nums = [0,1,2,3,4,_,_,_,_,_]
Explanation: Your function should return k = 5, with the first five elements of nums
being 0, 1, 2, 3, and 4 respectively.
It does not matter what you leave beyond the returned k (hence they are underscores).
My code to solve this problem is
var removeDuplicates = function(nums) {
const non_duplicates = [];
for (let i=0;i<=nums.length-1;i++){
if(!(non_duplicates.includes(nums[i]))){
non_duplicates.push(nums[i]);
}
}
console.log(non_duplicates)
return non_duplicates.length;
};
That console.log(non_duplicates) displays correct output in stdOut. But when I return non_duplictes it prints empty array in output. And when I return non_duplictes.length it returns some array rather than the length of that array.
Please don't suggest any other method to solve this problem. Just tell what is wrong with this code
You can see that problem here
Your solution doesn't modify the array inplace. That's the first problem.
A bigger problem is that your algorithm is with O(N^2) time complexity, due to includes call and given that "1 <= nums.length <= 3 * 104" your solution would be incredibly slow if it ever passes the tests.
The goal is to find a linear solution of the problem. One possible solution would be:
var removeDuplicates = function(nums) {
let j = 0;
for (let i = 1, len = nums.length; i < len; i++) {
if (nums[i] !== nums[j]) {
nums[++j] = nums[i];
}
}
return j + 1;
};
You can achieve that by using Set() Object.
let nums = [0,0,1,1,1,2,2,3,3,4];
const uniqueNums = [...new Set(nums)];
console.log(uniqueNums.length, uniqueNums);
You're returning the correct value but you are not overwriting the nums array with the non-duplicate values.
After calling your function, the return value should be 5 and the first 5 values in the passed-in nums array should be 0,1,2,3,4 (the value of the others doesn't matter).
Simplest solution that's compatible with your attempted solution is:
copy the values from non_duplicates into nums
return non_duplicates.length.
Here's a simple example of how to do this:
var removeDuplicates = function (nums) {
const non_duplicates = [];
for (let i = 0; i < nums.length; i++) {
if (!non_duplicates.includes(nums[i])) {
non_duplicates.push(nums[i]);
}
}
for (let i = 0; i < non_duplicates.length; i++) {
nums[i] = non_duplicates[i];
}
return non_duplicates.length;
};
Note: this is not the most efficient solution, and efficiency becomes important with the medium to hard Leetcode challenges, but it's simple, close to your intended solution, and it works.
I need to create function that creates and returns array. Its size needs to match the rows parameter, and each next element contains consecutive integers starting at 1. To call this function I need to use argument 5. Here below is what I wrote so far. Can you tell me what's wrong here?
function createArray(rows) {
for(let i = 1; i < rows.length; i++) {
console.log(rows[i]);
}return rows;
}
createArray(5);
You need to create an array and return it, whereas you return just rows which is a number. The idea of using a for loop is the best way to go. In that loop you just need to set the values in the array accordinlgy.
Another problem in your code is that rows is of type number and does have a property length but that does not have the desired value. So we just use rows in the for loop. We start the loop with i = 0 because array indices start at 0.
Code
function createArray(rows) {
let arr = new Array(rows);
for (let i = 0; i < rows; i++) {
arr[i] = i + 1;
}
return arr;
}
console.log(createArray(5));
We can not use length property for number. create an empty array and then push values into that array until required size is achieved.
function createArray(rows) {
var arr = [];
for(let i = 1; i <= rows; i++) {
arr.push(i);
}return arr;
}
createArray(5);
I think what you want is createArray(5) return [1,2,3,4,5] if that's the case you could do this
function createArray(rows) {
const arr = []
for(let i = 1; i <= rows; i++) {
arr.push(i);
}
return arr;
}
console.log(createArray(5));
The problem is, that rows.length is not available on 5, because 5 is a number.
You have to use an array as parameter:
Array(5) creates an array with the length of 5 and fill("hello") fills this array with "hello" values.
function createArray(rows) {
for (let i = 1; i < rows.length; i++) {
console.log(rows[i]);
}
return rows;
}
const rows = Array(5).fill("hello");
createArray(rows);
I don't know, if this is the behaviour you want, if not, I misunderstood your question.
I want to display an array without showing of indexes. The for loop returns the array indexes which is not showing in usual declaration.
I want to send an array like [1,2,3 ...] but after retrieving from for loop, I haven't the above format. How can I store my values as above.
var a = [];
for (var i = 1; i < 8; i++) {
a[i] = i;
};
console.log(a);
Outputs:
[1: 1, 2: 2 ...]
Desired output:
[1,2,3]// same as console.log([1,2,3])
Array indices start at zero, your loop starts at 1, with index 0 missing you have a sparse array that's why you get that output, you can use push to add values to an array without using the index.
var a = [];
for (var i = 1; i < 8; i++) {
a.push(i);
};
console.log(a);
The problem is that you start your array with 1 index, making initial 0 position being empty (so called "hole" in array). Basically you treat array as normal object (which you can do of course but it defeats the purpose of array structure) - and because of this browser console.log decides to shows you keys, as it thinks that you want to see object keys as well as its values.
You need to push values to array:
var a = [];
for (var i = 1; i < 8; i++) {
a.push(i);
};
I have to disagree with the answers provided here. The best way to do something like this is:
var a = new Array(7);
for (var i = 0; i < a.length; i++) {
a[i] = i + 1;
}
console.log(a);
Your code is making each index equal to i, so use it this way
var a = [];
for (var i = 1; i < 8; i++) {
a.push(i);
};
console.log(a);
Similar to this question - Array value count javascript
How would I go about doing this, except with dynamic values?
var counts = []
var dates= [ "28/05/2013", "27/05/2013", "28/05/2013", "26/05/2013", "28/05/2013" ];
How would I get a count of the duplicated array values? So how many 28/05/2013 etc. The dates are all dynamic, so I can't just search for set values. I just can't get my head around how I would do this.
I may just scrap this idea, and get the value count from the last 10 days or something... but this may come in handy later(if it is even possible to do this).
This will do it:
var counts = {};
for (var i=0; i<dates.length; i++)
if (dates[i] in counts)
counts[dates[i]]++;
else
counts[dates[i]] = 1;
The result will be
> counts
{
"28/05/2013": 3,
"27/05/2013": 1,
"26/05/2013": 1
}
Make counts an object to perform duplicate detection in constant time.
var counts = {}
for (var i = 0; i < dates.length; i++) {
var date = dates[i];
if (counts[date] === undefined) {
counts[date] = 0;
}
counts[date] += 1;
}
console.log(counts);
Try like this
Updated
var dates= [ "28/05/2013", "27/05/2013", "28/05/2013", "26/05/2013", "28/05/2013" ];
var findStr = "28/05/2013";
var indexs = dates.indexOf(findStr,0),count=0;
for (var i=0;i< dates.length;i++){
if (indexs >= 0){
indexs = dates.indexOf(findStr,indexs + 1);
count++;
}
}
alert(count);
See Demo
I have a comma separated string, out of which I need to create a new string which contains a random order of the items in the original string, while making sure there are no recurrences.
For example:
Running 1,2,3,1,3 will give 2,3,1 and another time 3,1,2, and so on.
I have a code which picks a random item in the original string, and then iterates over the new string to see if it does not exist already. If it does not exist - the item is inserted.
However, I have a feeling this can be improved (in C# I would have used a hashtable, instead of iterating every time on the new array). One improvement can be removing the item we inserted from the original array, in order to prevent cases where the random number will give us the same result, for example.
I'd be happy if you could suggest improvements to the code below.
originalArray = originalList.split(',');
for (var j = 0; j < originalArray.length; j++) {
var iPlaceInOriginalArray = Math.round(Math.random() * (originalArray.length - 1));
var bAlreadyExists = false;
for (var i = 0; i < newArray.length; i++) {
if (newArray[i].toString() == originalArray[iPlaceInOriginalArray].toString()) {
bAlreadyExists = true;
break;
}
}
if (!bAlreadyExists)
newArray.push(originalArray[iPlaceInOriginalArray]);
}
Thanks!
You can still use a 'hash' in javascript to remove duplicates. Only in JS they're called objects:
function removeDuplicates(arr) {
var hash = {};
for (var i=0,l=arr.length;i<l;i++) {
hash[arr[i]] = 1;
}
// now extract hash keys... ahem...
// I mean object members:
arr = [];
for (var n in hash) {
arr.push(n);
}
return arr;
}
Oh, and the select random from an array thing. If it's ok to destroy the original array (which in your case it is) then use splice:
function randInt (n) {return Math.floor(Math.random()*n)}
function shuffle (arr) {
var out = [];
while (arr.length) {
out.push(
arr.splice(
randInt(arr.length),1 ));
}
return out;
}
// So:
newArray = shuffle(
removeDuplicates(
string.split(',') ));
// If you sort the first array, it is quicker to skip duplicates, and you can splice each unique item into its random position as you build the new array.
var s= 'Function,String,Object,String,Array,Date,Error,String,String,'+
'Math,Number,RegExp,Group,Collection,Timelog,Color,String';
var A1= s.split(',').sort(), A2= [], tem;
while(A1.length){
tem= A1.shift();
while(A1[0]== tem) tem= A1.shift();
if(tem) A2.splice(Math.floor(Math.random()*A2.length), 0, tem);
}
alert(A2.join(', '))
With your solution, you are not guaranteed not to pick same number several times, thus leaving some others of them never being picked. If the number of elements is not big (up to 100), deleting items from the source array will give the best result.
Edit
originalArray = originalList.split(',');
for (var j = 0; j < originalArray.length; j++) {
var iPlaceInOriginalArray = Math.round(Math.random() * (originalArray.length - 1 - j));
var bAlreadyExists = false;
for (var i = 0; i < newArray.length; i++) {
if (newArray[i].toString() == originalArray[iPlaceInOriginalArray].toString()) {
bAlreadyExists = true;
break;
}
}
var tmp = originalArray[originalArray.length - 1 - j];
originalArray[originalArray.Length - 1 - j] = originalArray[iPlaceInOriginalArray];
originalArray[iPlaceInOriginalArray] = tmp;
if (!bAlreadyExists)
newArray.push(originalArray[iPlaceInOriginalArray]);
}