I am trying to understand what this mean?
What I am thinking is that phrase will pass a part of array, so this in this case eve to phrase.palindrome method. That method will take and run it through. First var len takes eve and remove 1 from it using length -1. This results in var len being assigned number two as the length of eve is 3. Now for is in use, so var i = 0; i <= len/2; i++.
now becomes var i = 1;1 <= 1; i++."is this correct"
I don't understand what going on here:
for (var i = 0; i <= len/2; i++) {
if (this.charAt(i) !== this.charAt(len-i)) {
return false;
Here is all of the the code:
String.prototype.palindrome = function() {
var len = this.length-1;
for (var i = 0; i <= len/2; i++) {
if (this.charAt(i) !== this.charAt(len-i)) {
return false;
}
}
return true;
};
var phrases = ["eve", "kayak", "mom", "wow", "Not a palindrome"];
for (var i = 0; i < phrases.length; i++) {
var phrase = phrases[i];
if (phrase.palindrome()) {
console.log("'" + phrase + "' is a palindrome");
} else {
console.log("'" + phrase + "' is NOT a palindrome");
}
}
The code is essentially iterating through the string from both directions, comparing the first and last characters (indexes 0 and len) then the second from first and second from last and so forth until you reach the middle. A word is a palindrome if and only if the first and last characters are the same and the second and second to last characters are the same and so forth.
Note, there is something very wrong with this code. While it is technically possible to mutate the prototypes of built-in types in Javascript you should never, ever, ever do it. You gain no functionality you wouldn't from a normal function, while badly violating the principle of least surprise. Treat all types from other libraries, including built ins as if they are closed for modification and open for extension.
I think this line has error:
for (var i = 0; i <= len/2; i++) {
Beacuse somethimes length can be 3,5,7... and that can be problem.
I added some using examples:
for (var i = 0; i <= Math.floor(len / 2); i++) {
// That same thing with floor in positive numbers, but in negative numbers that works like ceil.
for (var i = 0; i <= ~~(len / 2); i++) {
// That same thing with floor, we can think like this pollyfill of floor.
for (var i = 0; i <= ~~(len / 2) + (Math.abs(len)>len?-1:0); i++) {
I'm trying to get N ways of solves a N rook problem. The issue I am having is currently, I seem to get n*n solutions while it needs to be N! . Below is my code, I have written it in simple loops and functions, so it's quite long. Any help would be greatly appreciated
Note: Please ignore case for n = 2. I get some duplicates which I thought I would handle via JSON.stringify
var createMatrix = function (n) {
var newMatrix = new Array(n);
// build matrix
for (var i = 0; i < n; i++) {
newMatrix[i] = new Array(n);
}
for (var i = 0; i < n; i++) {
for (var j = 0; j < n; j++) {
newMatrix[i][j] = 0;
}
}
return newMatrix;
};
var newMatrix = createMatrix(n);
// based on rook position, greying out function
var collision = function (i, j) {
var col = i;
var row = j;
while (col < n) {
// set the row (i) to all 'a'
col++;
if (col < n) {
if (newMatrix[col][j] !== 1) {
newMatrix[col][j] = 'x';
}
}
}
while (row < n) {
// set columns (j) to all 'a'
row++;
if (row < n) {
if (newMatrix[i][row] !== 1) {
newMatrix[i][row] = 'x';
}
}
}
if (i > 0) {
col = i;
while (col !== 0) {
col--;
if (newMatrix[col][j] !== 1) {
newMatrix[col][j] = 'x';
}
}
}
if (j > 0) {
row = j;
while (row !== 0) {
row--;
if (newMatrix[i][row] !== 1) {
newMatrix[i][row] = 'x';
}
}
}
};
// checks position with 0 and sets it with Rook
var emptyPositionChecker = function (matrix) {
for (var i = 0; i < matrix.length; i++) {
for (var j = 0; j < matrix.length; j++) {
if (matrix[i][j] === 0) {
matrix[i][j] = 1;
collision(i, j);
return true;
}
}
}
return false;
};
// loop for every position on the board
loop1:
for (var i = 0; i < newMatrix.length; i++) {
var row = newMatrix[i];
for (var j = 0; j < newMatrix.length; j++) {
// pick a position for rook
newMatrix[i][j] = 1;
// grey out collison zones due to the above position
collision(i, j);
var hasEmpty = true;
while (hasEmpty) {
//call empty position checker
if (emptyPositionChecker(newMatrix)) {
continue;
} else {
//else we found a complete matrix, break
hasEmpty = false;
solutionCount++;
// reinitiaze new array to start all over
newMatrix = createMatrix(n);
break;
}
}
}
}
There seem to be two underlying problems.
The first is that several copies of the same position are being found.
If we consider the case of N=3 and we visualise the positions by making the first rook placed red, the second placed green and the third to be placed blue, we get these three boards:
They are identical positions but will count as 3 separate ones in the given Javascript.
For a 3x3 board there are also 2 other positions which have duplicates. The gets the count of unique positions to 9 - 2 - 1 -1 = 5. But we are expecting N! = 6 positions.
This brings us to the second problem which is that some positions are missed. In the case of N=3 this occurs once when i===j==1 - ie the mid point of the board.
This position is reached:
This position is not reached:
So now we have the number of positions that should be found as 9 - 2 - 1 - 1 +1;
There appears to be nothing wrong with the actual Javascript in as much as it is implementing the given algorithm. What is wrong is the algorithm which is both finding and counting duplicates and is missing some positions.
A common way of solving the N Rooks problem is to use a recursive method rather than an iterative one, and indeed iteration might very soon get totally out of hand if it's trying to evaluate every single position on a board of any size.
This question is probably best taken up on one of the other stackexchange sites where algorithms are discussed.
Test Cases:
(6, [1,3,2,6,1,2]) returns (pairs / 2) = 5
It does get the answer the thing is that is doing more than it needs to, It is possible just add some validation to know when he is adding same reversed index but it will only give it more to do. am looking to remove the unneeded work. can it be more reliable?
function returnOcurrences(k,ar){
debugger;
const letters = [new Set(ar)];
let pairs = 0;
for (let i = 0; i < ar.length; i++) {
for (let ii = 0; ii < ar.length; ii++) {
let a = ar[i] + ar[ii];
if (i != ii) {
if (a >= k) {
pairs += (a % k == 0) ? 1 : 0
}
}
}
}
return pairs/2;
}
What I assume you want to do is prevent the algorithm from checking e.g. ar[1] + ar[2], then ar[2] + ar[1] again.
To solve this, consider starting your inner loop from i + 1 and not from 0. This prevents the mentioned scenario from happening, and also prevents the algorithm from summing an element with itself (e.g. ar[0] + ar[0]). So no need to check anymore if i is equal to ii.
Why so? Assume the first iteration of the outer loop. You are checking the sum of ar[0] with ar[1], then with ar[2], ar[3], and so on.
On the second iteration of the outer loop, you are checking sums of ar[1] with other elements of the array. However, you already checked ar[0] + ar[1] in the previous iteration. So you start with ar[1] + ar[2], where ii = i + 1 = 2.
So the code becomes:
function returnOcurrences(k,ar){
const letters = [new Set(ar)]; //I don't see the purpose of this variable but okay
var pairs = 0;
for (var i = 0; i < ar.length; i++) {
for (var ii = i + 1; ii < ar.length; ii++) {
var a = ar[i] + ar[ii];
if (a >= k) {
pairs += (a % k == 0) ? 1 : 0
}
}
}
return pairs/2;
}
Hope this helps!
I am trying to write a Google Sheets script macro. How do I step through it to understand why the time is being exceeded?
My problem is the loop, when I set the iteration max(scenarios) to 46, the code seems to run fine, taking about 1-2 seconds. When the max is set to 47, it dies with max execution time exceeded (4-5 minutes). Whats going on?
function testing() {
var aa = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("Run
Program");
var scenarios = aa.getRange("H19").getValue();
for (i = 1; i <= scenarios; i++){
var ss =
SpreadsheetApp.getActiveSpreadsheet().getSheetByName("Sheet6");
var range = ss.getRange("b6:u6");
var min = 1 ;
var max = 20 ;
var numbers = []
for (var i = min; i <= max; i++) {
numbers.push(i);
}
shuffleArray(numbers)
var counter = 0;
for (var x = 1; x <= range.getWidth(); x++) {
for (var y = 1; y <= range.getHeight(); y++) {
range.getCell(y, x).setValue(numbers[counter]);
counter++;
}
}
var range = ss.getRange("v6:ao6");
var min = 21 ;
var max = 40 ;
var numbers = []
for (var i = min; i <= max; i++) {
numbers.push(i);
}
shuffleArray(numbers)
var counter = 0;
for (var x = 1; x <= range.getWidth(); x++) {
for (var y = 1; y <= range.getHeight(); y++) {
range.getCell(y, x).setValue(numbers[counter]);
counter++;
}
}
var range = ss.getRange("ap6:at6");
var min = 41 ;
var max = 45 ;
var numbers = []
for (var i = min; i <= max; i++) {
numbers.push(i);
}
shuffleArray(numbers)
var counter = 0;
for (var x = 1; x <= range.getWidth(); x++) {
for (var y = 1; y <= range.getHeight(); y++) {
range.getCell(y, x).setValue(numbers[counter]);
counter++;
}
}
}
// function Chart4() {
var spreadsheet = SpreadsheetApp.getActive();
spreadsheet.getRange('A1').activate();
spreadsheet.getSheetByName('Chart4').showSheet()
.activate();
spreadsheet.setActiveSheet(spreadsheet.getSheetByName('Chart4'),
true);
};
Your code needs a lot of help. Here's a tip to get you started.
As others have mentioned, you should call .getValues() on the whole range, which gives you a 2 dimensional array of cell values [[A1value,B1value,...],[A2val,B2val...],...]. You should grab the width and length first and assign to a variable. Reference that variable instead of calling the API in the loop conditions. In fact, since you know the ranges ahead of time, you should define all the ranges you'll be needing outside of the main for loop, as well as the spreadsheet (ss):
var aa = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("Run Program");
var ss = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("Sheet6");
var range1 = ss.getRange("b6:u6");
var range2 = ss.getRange("v6:ao6");
for (i = 1; i <= scenarios; i++) { ...
Scripts start taking a long time if you make repeated calls to the API.
Not sure exactly what your macro is trying to do, but here is a template for running this kind of loop and how you should think about it.
var range = ss.getRange(A1-style-address);
var values = range1.getValues();
var width = range1[0].length;
var height = range1.length;
var new_values = new Array();
for (var i = 0; i < height; i++) {
for (var j = 0; j < width; j++) {
//do something with values[i][j], like push to new_values
}
}
//something like:
//var new_range = ss.getRange(different A1-style address)
//new_range.setValues(new_array)
You'll have to make sure that the new array contains values in a 2 dimensional array that has the same dimensions as the range you're putting them into or it will throw an error.
I'll leave it to you to figure out how to modify the new_values array inside the loop to make sure it is the right size.
Here's a link to an overview of arrays in javascript if this is new for you, and here's some array documentation.
Range.getCell() call can be expensive sometimes and should be avoided. Use Range.getValues() and iterate over the two dimensional array. Also, instead of using active spreadsheet open spreadsheet by Id for unit testing. This way you will be able to debug/run from GAS editor directly. GAS editor usually catches such performance issues in the code and displays warnings pointing to the line number in the code.
I am trying to write a jQuery that will find the index of a specific value within a 7x7 2D array.
So if the value I am looking for is 0 then I need the function to search the 2D array and once it finds 0 it stores the index of the two indexes.
This is what I have so far, but it returns "0 0" (the initial values set to the variable.
Here is a jsFiddle and the function I have so far:
http://jsfiddle.net/31pj8ydz/1/
$(document).ready( function() {
var items = [[1,2,3,4,5,6,7],
[1,2,3,4,5,6,7],
[1,2,3,0,5,6,7],
[1,2,3,4,5,6,7],
[1,2,3,4,5,6,7],
[1,2,3,4,5,6,7],
[1,2,3,4,5,6,7]];
var row = 0;
var line = 0;
for (i = 0; i < 7; ++i) {
for (j = 0; i < 7; ++i) {
if (items[i, j] == '0,') {
row = i;
line = j;
}
}
}
$('.text').text(row + ' ' + line);
});
HTML:
<p class="text"></p>
Your if statement is comparing
if (items[i, j] == '0,')
Accessing is wrong, you should use [i][j].
And your array has values:
[1,2,3,4,5,6,7]
....
Your value '0,' is a string, which will not match numeric values inside the array, meaning that your row and line won't change.
First, you are accessing your array wrong. To access a 2D array, you use the format items[i][j].
Second, your array doesn't contain the value '0'. It doesn't contain any strings. So the row and line variables are never changed.
You should change your if statement to look like this:
if(items[i][j] == 0) {
Notice it is searching for the number 0, not the string '0'.
You access your array with the wrong way. Please just try this one:
items[i][j]
When we have a multidimensional array we access the an element of the array, using array[firstDimensionIndex][secondDimensionIndex]...[nthDimensionIndex].
That being said, you should change the condition in your if statement:
if( items[i][j] === 0 )
Please notice that I have removed the , you had after 0. It isn't needed. Also I have removed the ''. We don't need them also.
There are following problems in the code
1) items[i,j] should be items[i][j].
2) You are comparing it with '0,' it should be 0 or '0', if you are not concerned about type.
3) In your inner for loop you should be incrementing j and testing j as exit condition.
Change your for loop like bellow and it will work
for (i = 0; i < 7; i++) {
for (j = 0; j < 7; j++) {
if (items[i][j] == '0') {
row = i;
line = j;
}
}
}
DEMO
Note:-
1) Better to use === at the place of ==, it checks for type also. As you see with 0=='0' gives true.
2) Better to say i < items.length and j<items[i].length instead of hard-coding it as 7.
var foo;
items.forEach(function(arr, i) {
arr.forEach(function(val, j) {
if (!val) { //0 coerces to false
foo = [i, j];
}
}
}
Here foo will be the last instance of 0 in the 2D array.
You are doing loop wrong
On place of
for (i = 0; i < 7; ++i) {
for (j = 0; i < 7; ++i) {
if (items[i, j] == '0,') {
row = i;
line = j;
}
}
}
use this
for (i = 0; i < 7; i++) {
for (j = 0; j < 7; j++) {
if (items[i][j] == 0) {
row = i;
line = j;
}
}
}
Here is the demo
looks like you are still learning how to program. But here is an algorithm I've made. Analyze it and compare to your code ;)
var itens = [[1,2,3,4,5,6,7],
[1,2,3,4,5,6,7],
[1,2,3,0,5,6,7],
[1,2,3,4,5,6,7],
[1,2,3,4,5,6,7],
[1,2,3,4,5,6,7],
[1,2,3,4,5,6,7]];
var row = null;
var collumn = null;
for (var i = 0; i < itens.length; i++) {
for (var j = 0; j < itens[i].length; j++) {
if (itens[i][j] == 0) {
row = i;
collumn = j;
}
}
}
console.log(row, collumn);