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how to add 1 in last item of array in javascript [closed]

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I am solving one problem .but getting correct output for small array but my solution fail when array size is large
solution
/**
* #param {number[]} digits
* #return {number[]}
*/
var plusOne = function(digits) {
let str = parseInt(digits.join(''))+1+''
return str.split('')
};
Question
The digits are stored such that the most significant digit is at the head of the list, and each element in the array contain a single digit.
You may assume the integer does not contain any leading zero, except the number 0 itself.
Example 1:
Input: [1,2,3]
Output: [1,2,4]
Explanation: The array represents the integer 123.
Example 2:
Input: [4,3,2,1]
Output: [4,3,2,2]
Explanation: The array represents the integer 4321.
above cases are passed
failed cases
Input
[6,1,4,5,3,9,0,1,9,5,1,8,6,7,0,5,5,4,3]
Output
[6,1,4,5,3,9,0,1,9,5,1,8,6,7,0,5,0,0,0]
Expected
[6,1,4,5,3,9,0,1,9,5,1,8,6,7,0,5,5,4,4]

let str = parseInt(digits.join(''))+1+''
With too many array elements, you are simply creating a number that is outside of the integer range here.
An implicit conversion to a float has to happen, and with that you get the inherent loss of precision - which then leads to several zeros in those places at the end, when you reverse the process.
Access the last array element specifically, and add 1 to the value. But if that last element had the value 9 already, you will of course have to repeat that same process for the previous one … basic application of “carry the one”.
var input = [6,1,4,5,3,9,0,1,9,5,1,8,6,7,0,5,5,4,9];
var output = [];
// loop over input array in reverse order
for(var i=input.length-1, toadd = 1; i>-1; --i) {
// add value `toadd` to current digit
var incremented = input[i] + toadd;
if(incremented < 10) {
output.unshift(incremented); // add to front of output array
toadd = 0; // reset toadd for all following digits, if we had no overflow
}
else {
output.unshift(0); // overflow occurred, so we add 0 to front of array instead
}
}
console.log(output)
This does take an “overflow” for 9 digits at the end into account; it does not handle the case when all digits are 9 though, if you need to handle that edge case as well, please implement that yourself.

This one recursively checks the last digits:
const test1 = [6,1,4,5,3,9,0,1,9,5,1,8,6,7,0,5,5,4,3]
const test2 = [6,1,4,5,3,9,0,1,9,5,1,8,6,7,0,5,5,4,9]
const plusOne = function(digits) {
if(digits[digits.length - 1] === 9){
digits = [...plusOne(digits.slice(0, -1)), 0]
}else{
digits[digits.length - 1]++
}
return digits;
};
console.log(plusOne(test1));
console.log(plusOne(test2));

You could do something like this :
var arr = [6,1,4,5,3,9,0,1,9,5,1,8,6,7,0,5,5,4,3,9,9]
function plusOne(index){
if( index < 0 ) return ; // Base case
if(arr[index] === 9){
arr[index] = 0;
plusOne(index-1); // For carry ahead
}else{
arr[index] += 1
}
}
plusOne(arr.length-1) // start with last digit

Truncate zeros from string in javascript [closed]

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I see questions asked on truncating the leading zeros, but nothing found to solve my issue. I have a array of strings representing days returning from an api call.
Ex:
arr= ["061-094", "0561-0960", "000-005", "180+"];
arr.map(function(d){
<div>{d} days</div> // this returns 061-094 days
});
1) How can I remove the leading zeros so that it displays like:
61-94 days
561-960 days
0-5 days
2) How can display:
more than 180 days
for "180+" value?
Thanks

You can use map to generate a new array by testing each value, and if it matches the nn-nn pattern, split the string into numbers, convert to number (removes leading zeros but keeps "0" as a single value), then put them back as strings.
If the string matches the nn+ pattern, process it accordingly.
E.g.
var arr = ["061-094", "0561-0960", "000-005", "180+"];
var result = arr.map(function(v) {
// deal with nn-nn
if (/\d+-\d+/.test(v)) {
return v.split('-').map(s => +s).join('-');
}
// Deal with nn+
if (/\d+\+/.test(v)) {
return v.replace(/(\d+).*/, 'more than $1 days');
}
});
console.log(result);
If you want to wrap in HTML, then do that too.

Assuming there's no other patterns in your data than 000-000 or 180+:
arr = ["061-094", "0561-0960", "000-005", "180+", "90+"];
var result = arr.map(function(d){
if (d.substr(-1) == "+") {
return "<div>More than " + d.slice(0,-1) + " days</div>";
}
var parts = d.split("-");
var truncatedParts = [];
parts.map(function(part) {
truncatedParts.push(parseInt(part, 10));
});
return "<div>" + truncatedParts.join("-") + " days</div>" ;
});
console.log(result);

Have you tired making a String to remove all leading zeros?
String strPattern = "^0+";
This should remove all leading zeros but not trailing zeros.

Algorithm to convert any string to a 1-3 digit number [closed]

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I want to make an algorithm, for a NodeJS app, that converta any given string to a 1 to 3 digit number (better if the number is between 1-500).
e.g
ExampleString -> 214
Can anyone help me find a good solution?
EDIT:
I want to get a crime coefficient number from a username (string).

Ok, you can use JS function to get charCode of letter
let str = "some string example";
let sum = 0;
for (let i=0; i<str.length; i++) {
sum += parseInt(str[i].charCodeAt(0), 10); // Sum all codes
}
// Now we have some value as Number in sum, lets convert it to 0..1 value to scale to needed value
let rangedSum = parseFloat('0.' + String(sum)); // Looks dirty but works
let resultValue = Math.round(rangedSum * 500) + 1; // Same alogorythm as using Math.random(Math.round() * (max-min)) + min;
I hope it helps.
So as you are using nodejs, you can use crypto library to get md5 hash of string and then get it as HEX.
const crypto = require('crypto');
let valueHex = crypto.createHash('md5').update('YOUR STRING HERE').digest('hex');
// then get it as decimal based value
let valueDec = parseInt(valueHex, 16);
// and apply the same algorythm as above to scale it between 1-500

function coeficient() {
return Math.floor(Math.random() * 500) + 1;
}
console.log(coeficient());
console.log(coeficient());
console.log(coeficient());

How can I find the sum of each individual element in an array of long numbers? [closed]

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This question will need to be answered in Javascript.
For example, I have an array of phone numbers:
var phoneNumbers = ['123-434-4455', '123-495-8475', '484-728-3456'];
The phone number at index 0 (123-434-4455) would be added as 1+2+3+4+3+4+4+4+5+5, totaling to 35.
I'm guessing this will involve some kind of loop (for loops, or the method .forEach), because I will need to do this for multiple phone numbers in an array that will probably be randomly generated by a computer, so length and amount will vary.
Also, I'm wondering if the hyphen will matter, in which case I have found .replaceAll("-","");.
I've researched some other methods on here that involve .split, .parsInt, .map, .toString, .reduce, .digitSum, and more. They seem pretty complicated, especially since I'm in a beginning course (however I'm totally new to programming - this is my first post btw). Also, I'd rather not post the full question because I really want to figure it out alone, but this is the part I'm most stuck on. Forgive me if this has been answered previously! Like I said...new to programming.
I also need to determine which phone number has the last largest sum of digits, and use a return statement to return the required phone number in its’ original form.

You can use map and reduce array methods:
['123-434-4455', '123-495-8475', '484-728-3456'].map(function(str) {
return str.split('').reduce(function(a,b) {
return a + (+b || 0);
}, 0);
}); // [ 35, 48, 51 ]
Some notes:
split('') splits a string into an array of characters
+b coerces b into a number, e.g. "5" to 5 and "-" to NaN.
+b || 0 will return 0 if +b is falsy (0 or NaN), and +b otherwise

This code will do it:
var phoneNumbers = ["123-434-4455", "123-495-8475", "484-728-3456"];
for (var i=0; i<phoneNumbers.length; i++) {//For every phone number
var total=0; //create a total variable
var indNumbers = phoneNumbers[i].replace(/-/g, ""); //remove all dashes
for (var j=0; j<indNumbers.length; j++) {//loop for all digits
total+=parseFloat(indNumbers[j]);//add each digit to total
}
console.log(total);//do stuff with it here
}
All pretty standard javascript stuff. Only confusing bit I might have used is the .replace method - my parameter is /-/g which might look scary, but it's the equivalent of passing in "-" except it tells the function to replace ALL instances of the dash. If you do pass "-", it only replaces the first instance.
If you're a beginner, the things in this code you'll want to learn about are .replace, parseFloat for loops, and accessing strings using square bracket notation.

var phoneNumbers = ["123-434-4455", "123-495-8475", "484-728-3456"];
function crossSum(arr, pos) {
var sum = 0;
var a = arr[pos].split("-").join("").split("");
a.forEach(function(e, i) {
sum += parseInt(a[i]);
})
return sum;
}
document.write(crossSum(phoneNumbers, 0));
This function will return the cross-sum of
your phone-number.
Just use crossSum(phoneNumers, 0) // 0 is the fist number of phoneNumbers.
This will return the crossSum.

Adding on #millerbr answer. If you don't want to use .replace you can just use parseInt/parseFloat on every char, if it is not a number those functions returns NaN which can be checked with isNaN() function
var phoneNumbers = ["123-434-4455", "123-495-8475", "484-728-3456"];
for (var i=0; i < phoneNumbers.length; i++) { //For every phone number
var total=0; //create a total variable
for (var j=0; j < phoneNumbers.length; j++) { //loop for all digits
var parsedNumber = parseInt(phoneNumbers[j]); // parse string to number or NaN if "-"
if (!isNaN(parsedNumber)) { // Check if result is NaN (Not a Number).
total += parsedNumber; //add each digit to total
}
}
console.log(total);//do stuff with it here
}

Assuming that phoneNumbers is an array of strings, you can indeed loop through the entire array and then in each element in the array you can loop through the string and check if the character is a number. If so, add it to your sum and then when you finish each element in the array you have the total sum for it and you can add it to another array full of your sums.

How do I create a javascript elite planet name generator? [closed]

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I try to convert Tricky's script (that generates a name from elite) to javascript here:
https://github.com/rubo77/eliteNameGen/blob/master/elite.js
But I get stuck at this LPC-code by Tricky:
digrams=ABOUSEITILETSTONLONUTHNO..LEXEGEZACEBISOUSESARMAINDIREAERATENBERALAVETIEDORQUANTEISRION
...
pairs = digrams[24..<1];
...
names[0..<2]
I couldn't find a manual to LPC that would explain this syntax.
In the End I want to create a javascript, that creates a random planet name from the old C64 game Elite.
I also found a python version, (but that seems a bit more complicated to me)

Ok I managed to port the code over, but I had to tweak a bit of the algorithm. The one that is provide by Tricky, for some reason, produces non-unique names. I used the tweakseed function to tweak the seeds to generate a list of random names.
Answer
To answer the question above, #MattBurland is correct. You would replace the following code:
pairs = digrams[24..<1];
with
pairs = digrams.substring(24);
The following code, however, is actually printing out the list of names. So you're indexing an array - in which case:
names[0..<2]
becomes
for (var i = 0; i < (names.length - 2); i++) {
names[i]
}
Analysis
Just to give this some more depth. I've analyzed the code and realized that rotatel, twist, tweakseed, and next were just used to create random numbers. I don't know enough about LPC, but I think that at the time it probably didn't have a pseudo-random number generator.
A lot of this code can be removed and just replaced with Math.random. The key part of this entire program is the variable digram. This sequence of characters produces Alien-like names. I figure it probably has something to do with alternation of consonants and vowels. Grabbing them in pairs randomly will almost always produce some sort of consonant + vowel pairing. There is the odd time where you'll end up with a name like 'Rmrirqeg', but in most cases, the names appear Alien-like.
Port
Below is a direct port of the code. You can use this jsFiddle to see it in action, but it uses AngularJS to print out the names instead of printing out a list like the code provided. genNames will produce an array of names, which you can use for whatever reason you want.
Note this port only works on IE9+, since it uses map, reduce, and forEach. Replace these with loops if you plan on using this on IE8 or below.
You can tweak this to produce names longer or shorter. However, the length of the names is dependent on the pairs array. Either use Math.random or something to make it completely wild.
var digrams = "ABOUSEITILETSTONLONUTHNO" +
"..LEXEGEZACEBISOUSESARMAINDIREA.ERATENBERALAVETIEDORQUANTEISRION";
function rotatel(x) {
var tmp = (x & 255) * 2;
if (tmp > 255) tmp -= 255;
return tmp;
}
function twist(x) {
return (256 * rotatel(x / 256)) + rotatel(x & 255);
}
function next(seeds) {
return seeds.map(function(seed) {
return twist(seed);
});
}
function tweakseed(seeds) {
var tmp;
tmp = seeds.reduce(function(total, seed) {
return total += seed;
}, 0);
return seeds.map( function ( seed, index, arr ) {
return arr[index + 1] || (tmp & 65535)
});
};
function makename(pairs, seeds)
{
var name = [];
/* Modify pair if you want to have names shorter or longer than 8 chars */
/* I'll leave that as an exercise for you. */
var pair = [0, 0, 0, 0];
var longname = seeds[0] & 64;
pair = pair.map(function() {
seeds = tweakseed(seeds);
return 2 * ((seeds[2] / 256) & 31);
});
pair.forEach(function(value, index, arr) {
if (longname || ( index < (arr.length - 1))) {
name.push(pairs[value]);
name.push(pairs[value + 1]);
}
});
return name.join('').toLowerCase()
.replace(/^\w/, function(letter) {
return letter.toUpperCase();
});
}
function genNames()
{
var names = [];
var pairs;
var num = 256;
var seeds = [23114, 584, 46931];
pairs = digrams.substring(24);
while (--num) {
names.push( makename(pairs, seeds) );
seeds = tweakseed(next(seeds));
}
return names;
}

For the range operator in LPC, this link helps:
http://www.unitopia.de/doc/LPC/operators.html
expr1[expr2..expr3] Extracts a
piece from an array or string.
expr2 or expr3 may be omitted, default is the begin
or end of expr1.
Negative numbers for expr2 or expr3
mean ``count from before the beginning'', i.e.
foo[-2..-1] is an empty array or string.
foo[<2..<1] gives the 2nd and last element of
the array resp. chars of the string.
So I'm guessing that:
pairs = digrams[24..<1];
Means get the substring starting at index 24 to the end of the string?