I'm having a little trouble with my attempt at this problem. Code Below:
function pasc(n){
var result = [[1]];
for (var row = 1; row < n; row++){
for (var col = 1; col <= row; col++){
result[row][col] = result[row - 1][col] + result[row - 1][col - 1];
}
}
return result;
}
pasc(10)
for (var i = 0; i < result.length; i++){
document.write(result[i]+"<br>");
}
It seems the problem hinges on assigning values to an array using an expression like myArray[1][1] = "foo"
I'm confused about this because I can do this: var myArray = []; myArray[4] = "foo" which seems to suggest that an element can be created at an arbitrary position in a 1 dimensional array, but not with 2 dimensions.
Any help with clearing up my misconceptions appreciated.
The Pascal's Triangle can be printed using recursion
Below is the code snippet that works recursively.
We have a recursive function pascalRecursive(n, a) that works up till the number of rows are printed. Each row is a element of the 2-D array ('a' in this case)
var numRows = 10,
triangle,
start,
stop;
// N is the no. of rows/tiers
// a is the 2-D array consisting of the row content
function pascalRecursive(n, a) {
if (n < 2) return a;
var prevRow = a[a.length-1];
var curRow = [1];
for (var i = 1; i < prevRow.length; i++) {
curRow[i] = prevRow[i] + prevRow[i-1];
}
curRow.push(1);
a.push(curRow);
return pascalRecursive(n-1, a); // Call the function recursively
}
var triangle = pascalRecursive(numRows, [[1]]);
for(var i = 0; i < triangle.length; i++)
console.log(triangle[i]+"\n");
JavaScript doesn't have two-dimensional arrays. What it does have is arrays that happen to contain other arrays. So, yes, you can assign a value to any arbitrary position in an array, and the array will magically make itself big enough, filling in any gaps with 'undefined'... but you can't assign a value to any position in a sub-array that you haven't explicitly created yet. You have to assign sub-arrays to the positions of the first array before you can assign values to the positions of the sub-arrays.
Replacing
for (var row = 1; row < n; row++){
for (var col = 1; col <= row; col++){
with
for (var row = 1; row < n; row++){
result[row] = [];
for (var col = 1; col <= row; col++){
should do it. Assuming all of your indexing logic is correct, anyway. You've got some problems there, too, since your initial array only contains a single value, so result[row][col] = result[row - 1][col] + result[row - 1][col - 1]; is accessing at least one cell that has never been defined.
Thanks Logan R. Kearsley. I have now solved it:
function pasc(n){
var result = [];
result[0] = [1];
result[1] = [1,1];
for (var row = 2; row < n; row++){
result[row] = [1];
for (var col = 1; col <= row -1; col++){
result[row][col] = result[row-1][col] + result[row-1][col-1];
result[row].push(1);
}
}
return result;
}
for (var i = 0; i < pasc(10).length; i++){
document.write(pasc(10)[i]+"<br>");
console.log(pasc(10)[i]+"<br>");
}
you can create Pascal's triangle using below code:
function pascal(n) {
var arr = [];
if (n == 1) {
arr[0] = [];
arr[0][0] = 1;
} else if (n == 2) {
arr[0] = [];
arr[0][0] = 1;
arr[1] = [];
arr[1][0] = 1;
arr[1][1] = 1;
} else if (n > 2) {
arr[0] = [];
arr[1] = [];
arr[0][0] = 1;
arr[1][0] = 1;
arr[1][1] = 1;
for (i = 2; i < n; i++) {
arr[i] = [];
arr[i][0] = 1;
for (j = 1; j < i; j++) {
arr[i][j] = arr[i - 1][j - 1] + arr[i - 1][j];
}
arr[i][j] = 1;
}
}
console.log(arr);
for (i = 0; i < arr.length; i++) {
console.log(arr[i].join(' '))
}
}
function pascal(n) {
var arr = [];
if (n == 1) {
arr[0] = [];
arr[0][0] = 1;
} else if (n == 2) {
arr[0] = [];
arr[0][0] = 1;
arr[1] = [];
arr[1][0] = 1;
arr[1][1] = 1;
} else if (n > 2) {
arr[0] = [];
arr[1] = [];
arr[0][0] = 1;
arr[1][0] = 1;
arr[1][1] = 1;
for (i = 2; i < n; i++) {
arr[i] = [];
arr[i][0] = 1;
for (j = 1; j < i; j++) {
arr[i][j] = arr[i - 1][j - 1] + arr[i - 1][j];
}
arr[i][j] = 1;
}
}
console.log(arr);
for (i = 0; i < arr.length; i++) {
console.log(arr[i].join(' '))
}
}
pascal(5)
This function will calculate Pascal's Triangle for "n" number of rows. It will create an object that holds "n" number of arrays, which are created as needed in the second/inner for loop.
function getPascalsTriangle(n) {
var arr = {};
for(var row = 0; row < n; row++) {
arr[row] = [];
for(var col = 0; col < row+1; col++) {
if(col === 0 || col === row) {
arr[row][col] = 1;
} else {
arr[row][col] = arr[row-1][col-1] + arr[row-1][col];
}
}
}
return arr;
}
console.log(getPascalsTriangle(5));
Floyd triangle
You can try the following code for a Floyd triangle
var prevNumber=1,i,depth=10;
for(i=0;i<depth;i++){
tempStr = "";j=0;
while(j<= i){
tempStr = tempStr + " " + prevNumber;
j++;
prevNumber++;
}
console.log(tempStr);
}
You can create arbitrary 2d arrays and store it in there and return the correct Pascal.
JavaScript does not have a special syntax for creating multidimensional arrays. A common workaround is to create an array of arrays in nested loops.
source
Here is my version of the solution
function pascal(input) {
var result = [[1], [1,1]];
if (input < 0) {
return [];
}
if (input === 0) {
return result[0];
}
for(var j = result.length-1; j < input; j++) {
var newArray = [];
var firstItem = result[j][0];
var lastItem = result[j][result[j].length -1];
newArray.push(firstItem);
for (var i =1; i <= j; i++) {
console.log(result[j][i-1], result[j][i]);
newArray.push(sum(result[j][i-1], result[j][i]));
}
newArray.push(lastItem);
result.push(newArray);
}
return result[input];
}
function sum(one, two) {
return one + two;
}
Here is the code i created for pascal triangle in javascript
'use strict'
let noOfCoinFlipped = 5
let probabiltyOfnoOfHead = 2
var dataStorer = [];
for(let i=0;i<=noOfCoinFlipped;i++){
dataStorer[i]=[];
for(let j=0;j<=i;j++){
if(i==0){
dataStorer[i][j] = 1;
}
else{
let param1 = (j==0)?0:dataStorer[i-1][j-1];
let param2 = dataStorer[i-1][j]?dataStorer[i-1][j]:0;
dataStorer[i][j] = param1+param2;
}
}
}
let totalPoints = dataStorer[noOfCoinFlipped].reduce((s,n)=>{return s+n;})
let successPoints = dataStorer[noOfCoinFlipped][probabiltyOfnoOfHead];
console.log(successPoints*100/totalPoints)
Here is the link as well
http://rextester.com/TZX59990
This is my solve:
function pascalTri(n){
let arr=[];
let c=0;
for(let i=1;i<=n;i++){
arr.push(1);
let len=arr.length;
if(i>1){
if(i>2){
for(let j=1;j<=(i-2);j++){
let idx=(len-(2*i)+j+2+c);
let val=arr[idx]+arr[idx+1];
arr.push(val);
}
c++;
}
arr.push(1);
}
}
return arr;
}
let pascalArr=pascalTri(7);
console.log(pascalArr);
here is the pattern for n = 3
#
##
###
here is js code to print this.
function staircase(n) {
for(var i=0 ; i<n ; i++) {
for(var j=n-1 ; j>i ; j--)
process.stdout.write(" ");
for(var k=0 ; k<=i; k++) {
process.stdout.write("#");
}
process.stdout.write("\n");
}
}
class PascalTriangle {
constructor(n) {
this.n = n;
}
factoriel(m) {
let result = 1;
if (m === 0) {
return 1;
}
while (m > 0) {
result *= m;
m--;
}
return result;
}
fill() {
let arr = [];
for (let i = 0; i < this.n; i++) {
arr.push([]);
}
for (let i = 0; i < arr.length; i++) {
for (let j = 0; j <= i; j++) {
arr[i].push(this.factoriel(i) / (this.factoriel(j) * this.factoriel(i - j)));
}
}
return arr;
}
}
var m = prompt("enter number:");
var arrMain = new Array();
for (var i = 0; i < m; i++) {
arrMain[i] = [];
}
for (var i = 0; i < m; i++) {
if (i == 0) {
arrMain[i] = [1];
} else if (i == 1) {
(arrMain[i]) = [1, 1];
} else {
for (var j = 0; j <= i; j++) {
if (j == 0 || j == arrMain[i - 1].length) {
arrMain[i][j] = 1;
} else {
arrMain[i][j] = arrMain[i - 1][j] + arrMain[i - 1][j - 1];
}
}
}
document.write(arrMain[i] + "<br>");
}
This is my take on this problem by gaining access to the previous row.
const generate = numRows => {
const triangle = [[1]]
for (let i = 1; i < numRows; i++) {
// Previous row
const previous = triangle[i - 1]
// Current row
const current = new Array(i + 1).fill(1)
// Populate the current row with the previous
// row's values
for (let j = 1; j < i; j++) {
current[j] = previous[j - 1] + previous[j]
}
// Add to triangle result
triangle.push(current)
}
return triangle
}
Related
I am currently doing a codewars problem, and I think I almost got it however, I ran across a problem when sorting index values with the same letter. link to problem is here. https://www.codewars.com/kata/5782dd86202c0e43410001f6
function doMath(s) {
let strSplit = s.split(' ');
let clonedArr = strSplit.slice();
for (let i = 0; i < strSplit.length; i++) {
for (let j = 0; j < strSplit[i].length; j++) {
let current = strSplit[i][j];
if (isNaN(current)) {
let letter = current;
strSplit[i] = strSplit[i].replace(letter, '');
strSplit[i] = letter + strSplit[i];
}
}
}
let sortedArr = strSplit.sort();
console.log(sortedArr);
// ["b900", "y369", "z123", "z246", "z89"]
let noLetterArr = sortedArr.map(x => {
return x.slice(1);
});
let numberArr = noLetterArr.map(y => {
return +y;
})
let firstEl = numberArr[0];
for (let i = 1; i < numberArr.length; i++) {
if (numberArr.indexOf(numberArr[i]) % 4 == 1) {
firstEl += numberArr[i];
}
if (numberArr.indexOf(numberArr[i]) % 4 == 2) {
firstEl -= numberArr[i];
}
if (numberArr.indexOf(numberArr[i]) % 4 == 3) {
firstEl *= numberArr[i];
}
}
return firstEl;
}
console.log(doMath('24z6 1z23 y369 89z 900b'));
I would like to sort the sortedArr the ones with the same letter by how they first appeared in string. So since "z246" appeared first in the original string. I would like to have that before "1z23". I had a hard time creating a function for that.
var al = [];
function doMath(s) {
var ar = s.split(" ");
for (let i = 0; i < ar.length; i++) {
for (let char of ar[i]) {
let temp = char.match(/[a-z]/i);
if (temp) {
al[i] = char;
ar[i] = ar[i].replace(char, '');
ar[i] = char + ar[i];
}
}
}
al = al.sort();
//New Sort Logic to pass above test case and others too
var n = [];
for (let i = 0; i < al.length; i++) {
for (let j = 0; j < ar.length; j++) {
if (ar[j].startsWith(al[i]) && !n.includes(ar[j])) {
n.push(ar[j]);
}
}
}
var result = parseInt(n[0].substr(1)),
count = 1;
for (let i = 1; i < n.length; i++) {
if (count == 1) {
result = result + parseInt(n[i].substr(1));
count++;
} else if (count == 2) {
result = result - parseInt(n[i].substr(1));
count++;
} else if (count == 3) {
result = result * parseInt(n[i].substr(1));
count++;
} else if (count == 4) {
result = result / parseInt(n[i].substr(1));
count = 1;
}
}
return Math.round(result);
}
So I am building Tetris. After creating an array, data, I am trying to implement gravity by checking
every string in an array if it's is "full" as well as being able the space below it being empty. However, it is giving me an error that suggests that something is undefined. The I tried a for loop and a for...of loop, as well as Googling it.Why do I get this error, and how can I fix it?
const editor = document.getElementById("edit");
var data = [];
function array(x, text) {
var y = [];
for (var i = 0; i < x - 1; i++) {
y.push(text);
}
return y;
}
for (var i = 0; i < 20; i++) {
data.push(array(10, "b"));
}
function draw() {
var j;
var i;
var dataOut = data;
for (i = 0; i < data.length; i++) {
for (j = 0; j < data[i].length; j++) {
if (data[i][j] == "a" && data[i + 1][j] == "b") {
if (i < data.length - 1) {
dataOut[i][j] = "b";
dataOut[i + 1][j] = "a";
}
}
}
}
data = dataOut;
console.log(data);
requestAnimationFrame(draw);
}
data[0][4] = "a";
requestAnimationFrame(draw);
with for-of-loop you iterate only objects/values of array and not indexes.
use only for-loop in order to use indexes
const editor = document.getElementById("edit");
var data = [];
function array(x, text) {
var y = [];
for (var i = 0; i < x - 1; i++) {
y.push(text);
}
return y;
}
for (var i = 0; i < 20; i++) {
data.push(array(10, "b"));
}
function draw() {
var dataOut = data;
for (let i = 0; i < data.length - 1; i++) { // logical error here
for (let j = 0; j < data.length; j++) {
if (data[i][j] == "a" && data[i + 1][j] == "b") {
if (i < data.length - 1) {
dataOut[i][j] = "b";
dataOut[i + 1][j] = "a";
}
}
}
}
data = dataOut;
console.log(data);
requestAnimationFrame(draw);
}
data[0][4] = "a";
requestAnimationFrame(draw);
A simple example of for-of-loop
const arr = ["aa","bb"]
for(let a of arr) console.log(a);
// will print
/*
aa
bb
*/
for(let a = 0; a < arr.length; a++) console.log(a);
// will print
/*
0
1
*/
I am trying to write an insertion sort function that works from right to left.
Not in descending order. I just am not understanding why this code would not properly sort numbers.
function reverseInsertionSort(arr) {
for(var i = arr.length -1; i >0; i--)
var val = arr[i];
var j;
for(j = i; j > 0 && arr[j-1] < val; j--) {
arr[j-1] = arr[j]; }
va=arr[j]; }
function insertionSort(arr) {
for(var i = 1; i < arr.length; i++) {
var val = arr[i];
var j;
for(j = i; j > 0 && arr[j-1] > val; j--) {
arr[j] = arr[j-1]; }
arr[j] = val; }
}
arr[j] = val;
}
}
var length = Math.floor(Math.random()*100)+1;
var arr = new Array();
for(let i = 0; i < length; i++) {
arr.push(Math.floor(Math.random()*10000)+1);
}
var arr2= arr.slice();
reverseInsertionSort(arr2);
console.log(arr2)
It is not sorted, and the output ends in undefined.
arr is being used to test the insertionsort fun
Happy to accept constructive criticism.
This will work.
function reverseInsertionSort(arr) {
for(var i = arr.length-2; i>=0; i--) {
var value = arr[i];
var j;
for(j = i; ((j < arr.length) && (arr[j+1] > value)); j++){
arr[j] = arr[j+1];
}
arr[j] = value;
}
return arr;
}
//test
var inputArray = [3,2,4,5,1,10,23];
var resultArray = reverseInsertionSort(inputArray);
console.log(resultArray); //[23, 10, 5, 4, 3, 2, 1]
You should start the outer loop from the last element ie. len-1. The undefined member of the array is created due to your outer loop starting from arr.length .
Try this :
function insSort(arr){
for(var i=arr.length-1;i>=0;i--){
key=arr[i];
j=i+1;
while(j<arr.length&&arr[j]<=key){
arr[j-1]=arr[j];
j++;
}
arr[j-1]=key;
}
}
var length = Math.floor(Math.random()*100)+1;
var arr = new Array();
for(let i = 0; i < length; i++) {
arr.push(Math.floor(Math.random()*10000)+1);
}
console.log(arr);
insSort(arr);
console.log(arr);
I want to count how many times needed for an array to be sorted
var array = [4,2,3,1]
var yourCounter = 0;
for (var i = 0; i < array.length; i++) {
for (var j = 1; j < array.length-j; j++)
if (array[j - 1] > array[j]) {
yourCounter++;
} }
it will return 4 , it should be 5
but if I input array [1,2,3] will correctly return 0 , and if I input array [3,2,1] it will correctly return 3
You could take the given code and swap the values while counting.
for (int i = 0; i < n; i++) {
for (int j = 0; j < n - 1; j++) {
// Swap adjacent elements if they are in decreasing order
if (a[j] > a[j + 1]) {
swap(a[j], a[j + 1]);
}
}
}
var array = [4, 2, 3, 1],
counter = 0,
i, j, n = array.length;
for (i = 0; i < n; i++) {
for (j = 0; j < n - 1; j++) {
if (array[j] > array[j + 1]) {
[array[j + 1], array[j]] = [array[j], array[j + 1]];
++counter;
}
}
}
console.log(counter);
console.log(array);
I found the solution
var a = [4,2,3,1]
function sortArray(a){
let swapCount = 0;
let swapOccurred = true;
let index = 0;
while (swapOccurred == true && index < a.length){
swapOccurred == false;
if (a[index] > a[index+1]){
let holder = a[index]
a[index] = a[index+1];
a[index+1] = holder;
swapOccurred == true;
swapCount ++;
index = -1;
}
index ++
}
function countSwaps(a) {
let swapCount = 0;
[a, swapCount] = sortArray(a)
console.log(swapCount)
}
return [a, swapCount]
}
I have the following array as an example;
let arr = [['red','blue','pink],['dog','cat','bird'],['loud', 'quiet']]
I need to write a generalized function that prints all combinations of one word from the first vector, one word from the second vector, etc. I looked up some codes on here but they are all recursion or working only with the specific array. How can I write this code without recursion?
let allComb = function(arr) {
if (arr.length == 1) {
return arr[0];
} else {
let result = [];
let arrComb = allComb(arr.slice(1));
for (let i = 0; i < arrComb.length; i++) {
for (let j = 0; j < arr[0].length; j++) {
result.push(arr[0][j] + ' ' + arrComb[i]);
}
}
return result;
}
}
allComb(arr)
This version uses a single increment per cycle technique with no recursion.
let arr = [
['red', 'blue', 'pink'],
['dog', 'cat', 'bird'],
['loud', 'quiet']
];
function allComb(arr) {
var total = 1;
var current = [];
var result = [];
for (var j = 0; j < arr.length; j++) {
total *= arr[j].length;
current[j] = 0;
}
for (var i = 0; i < total; i++) {
var inc = 1;
result[i] = "";
for (var j = 0; j < arr.length; j++) {
result[i] += arr[j][current[j]] + ' ';
if ((current[j] += inc) == arr[j].length)
current[j] = 0;
else
inc = 0;
}
}
return (result);
}
console.log(allComb(arr));
You may do as follows;
var arr = [['red','blue','pink'],['dog','cat','bird'],['loud', 'quiet']],
res = arr.reduce((p,c) => p.reduce((r,x) => r.concat(c.map(y => x + " " + y)),[]));
console.log(res);