1
11
12
1121
122111
112213
122211
....
I was trying to solve this problem. It goes like this.
I need to check the former line and write: the number and how many time it was repeated.
ex. 1 -> 1(number)1(time)
var antsArr = [[1]];
var n = 10;
for (var row = 1; row < n; row++) {
var lastCheckedNumber = 0;
var count = 1;
antsArr[row] = [];
for (var col = 0; col < antsArr[row-1].length; col++) {
if (lastCheckedNumber == 0) {
lastCheckedNumber = 1;
antsArr[row].push(lastCheckedNumber);
} else {
if (antsArr[row-1][col] == lastCheckedNumber) {
count++;
} else {
lastCheckedNumber = antsArr[row-1][col];
}
}
}
antsArr[row].push(count);
antsArr[row].push(lastCheckedNumber);
}
for (var i = 0; i < antsArr.length; i++) {
console.log(antsArr[i]);
}
I have been on this since 2 days ago.
It it so hard to solve by myself. I know it is really basic code to you guys.
But still if someone who has a really warm heart help me out, I will be so happy! :>
Try this:
JSFiddle Sample
function lookAndSay(seq){
var prev = seq[0];
var freq = 0;
var output = [];
seq.forEach(function(s){
if (s==prev){
freq++;
}
else{
output.push(prev);
output.push(freq);
prev = s;
freq = 1;
}
});
output.push(prev);
output.push(freq);
console.log(output);
return output;
}
// Sample: try on the first 11 sequences
var seq = [1];
for (var n=0; n<11; n++){
seq = lookAndSay(seq);
}
Quick explanation
The input sequence is a simple array containing all numbers in the sequence. The function iterates through the element in the sequence, count the frequency of the current occurring number. When it encounters a new number, it pushes the previously occurring number along with the frequency to the output.
Keep the iteration goes until it reaches the end, make sure the last occurring number and the frequency are added to the output and that's it.
I am not sure if this is right,as i didnt know about this sequence before.Please check and let me know if it works.
var hh=0;
function ls(j,j1)
{
var l1=j.length;
var fer=j.split('');
var str='';
var counter=1;
for(var t=0;t<fer.length;t++)
{
if(fer[t]==fer[t+1])
{
counter++;
}
else
{
str=str+""+""+fer[t]+counter;
counter=1;
}
}
console.log(str);
while(hh<5) //REPLACE THE NUMBER HERE TO CHANGE NUMBER OF COUNTS!
{
hh++;
//console.log(hh);
ls(str);
}
}
ls("1");
You can check out the working solution for in this fiddle here
You can solve this by splitting your logic into different modules.
So primarily you have 2 tasks -
For a give sequence of numbers(say [1,1,2]), you need to find the frequency distribution - something like - [1,2,2,1] which is the main logic.
Keep generating new distribution lists until a given number(say n).
So split them into 2 different functions and test them independently.
For task 1, code would look something like this -
/*
This takes an input [1,1,2] and return is freq - [1,2,2,1]
*/
function find_num_freq(arr){
var freq_list = [];
var val = arr[0];
var freq = 1;
for(i=1; i<arr.length; i++){
var curr_val = arr[i];
if(curr_val === val){
freq += 1;
}else{
//Add the values to the freq_list
freq_list.push([val, freq]);
val = curr_val;
freq = 1;
}
}
freq_list.push([val, freq]);
return freq_list;
}
For task 2, it keeps calling the above function for each line of results.
It's code would look something like this -
function look_n_say(n){
//Starting number
var seed = 1;
var antsArr = [[seed]];
for(var i = 0; i < n; i++){
var content = antsArr[i];
var freq_list = find_num_freq(content);
//freq_list give an array of [[ele, freq],[ele,freq]...]
//Flatten so that it's of the form - [ele,freq,ele,freq]
var freq_list_flat = flatten_list(freq_list);
antsArr.push(freq_list_flat);
}
return antsArr;
}
/**
This is used for flattening a list.
Eg - [[1],[1,1],[1,2]] => [1,1,1,1,2]
basically removes only first level nesting
**/
function flatten_list(li){
var flat_li = [];
li.forEach(
function(val){
for(ind in val){
flat_li.push(val[ind]);
}
}
);
return flat_li;
}
The output of this for the first 10 n values -
OUTPUT
n = 1:
[[1],[1,1]]
n = 2:
[[1],[1,1],[1,2]]
n = 3:
[[1],[1,1],[1,2],[1,1,2,1]]
n = 4:
[[1],[1,1],[1,2],[1,1,2,1],[1,2,2,1,1,1]]
n = 5:
[[1],[1,1],[1,2],[1,1,2,1],[1,2,2,1,1,1],[1,1,2,2,1,3]]
n = 6:
[[1],[1,1],[1,2],[1,1,2,1],[1,2,2,1,1,1],[1,1,2,2,1,3],[1,2,2,2,1,1,3,1]]
n = 7:
[[1],[1,1],[1,2],[1,1,2,1],[1,2,2,1,1,1],[1,1,2,2,1,3],[1,2,2,2,1,1,3,1],[1,1,2,3,1,2,3,1,1,1]]
n = 8:
[[1],[1,1],[1,2],[1,1,2,1],[1,2,2,1,1,1],[1,1,2,2,1,3],[1,2,2,2,1,1,3,1],[1,1,2,3,1,2,3,1,1,1],[1,2,2,1,3,1,1,1,2,1,3,1,1,3]]
n = 9:
[[1],[1,1],[1,2],[1,1,2,1],[1,2,2,1,1,1],[1,1,2,2,1,3],[1,2,2,2,1,1,3,1],[1,1,2,3,1,2,3,1,1,1],[1,2,2,1,3,1,1,1,2,1,3,1,1,3],[1,1,2,2,1,1,3,1,1,3,2,1,1,1,3,1,1,2,3,1]]
So. I have 4 for loops inside other for loops in JS, and my code appears (FireBug agrees with me) that my code is syntactically sound, and yet it refuses to work. I'm attempting to calculate the key length in a vigenere cipher through the use of the Index of Coincidence, and Kappa tests <- if that helps any.
My main problem is that the task seems to be too computationally intensive for Javascript to run, as Firefox shoots up past 1GB of memory usage, and 99% CPU when I attempt to run the keylengthfinder() function. Any ideas of how to solve this problem, even if it takes much longer to calculate, would be greatly appreciated. Here's a link to the same code - http://pastebin.com/uYPBuZZz - Sorry about any indenting issues in this code. I'm having issues putting it on the page correctly.
function indexofcoincidence(text){
text = text.split(" ").join("").toUpperCase();
var textL = text.length;
var hashtable = [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0];
var alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
for (d=0; d<=25; d++) {
for (i=0; i < textL; i++){
if (text.charAt(i) === alphabet.charAt(d)){
hashtable[d] = hashtable[d] + 1;
}
}
}
var aa = hashtable[0]/textL;
var A = aa*aa;
var bb = hashtable[1]/textL;
var B = bb*bb;
var cc = hashtable[2]/textL;
var C = cc*cc;
var dd = hashtable[3]/textL;
var D = dd*dd;
var ee = hashtable[4]/textL;
var E = ee*ee;
var ff = hashtable[5]/textL;
var F = ff*ff;
var gg = hashtable[6]/textL;
var G = gg*gg;
var hh = hashtable[7]/textL;
var H = hh*hh;
var ii = hashtable[8]/textL;
var I = ii*ii;
var jj = hashtable[9]/textL;
var J = jj*jj;
var kk = hashtable[10]/textL;
var K = kk*kk;
var ll = hashtable[11]/textL;
var L = ll*ll;
var mm = hashtable[12]/textL;
var M = mm*mm;
var nn = hashtable[13]/textL;
var N = nn*nn;
var oo = hashtable[14]/textL;
var O = oo*oo;
var pp = hashtable[15]/textL;
var P = pp*pp;
var qq = hashtable[16]/textL;
var Q = qq*qq;
var rr = hashtable[17]/textL;
var R = rr*rr;
var ss = hashtable[18]/textL;
var S = ss*ss;
var tt = hashtable[19]/textL;
var T = tt*tt;
var uu = hashtable[20]/textL;
var U = uu*uu;
var vv = hashtable[21]/textL;
var V = vv*vv;
var ww = hashtable[22]/textL;
var W = ww*ww;
var xx = hashtable[23]/textL;
var X = xx*xx;
var yy = hashtable[24]/textL;
var Y = yy*yy;
var zz = hashtable[25]/textL;
var Z = zz*zz;
var Kappa = A+B+C+D+E+F+G+H+I+J+K+L+M+N+O+P+Q+R+S+T+U+V+W+X+Y+Z;
var Top = 0.027*textL;
var Bottom1 = 0.038*textL + 0.065;
var Bottom2 = (textL - 1)*Kappa;
var KeyLength = Top/(Bottom2 - Bottom1) ;
return Kappa/0.0385;
}
function keylengthfinder(text){
// Average Function Definition
Array.prototype.avg = function() {
var av = 0;
var cnt = 0;
var len = this.length;
for (var i = 0; i < len; i++) {
var e = +this[i];
if(!e && this[i] !== 0 && this[i] !== '0') e--;
if (this[i] == e) {av += e; cnt++;}
}
return av/cnt;
}
// Begin the Key Length Finding
var textL = text.length;
var hashtable = new Array(0,0,0,0,0,0,0,0,0,0,0,0);
for (a = 0; a <= 12; a++){ // This is the main loop, testing each key length
var stringtable = [];
for (z = 0; z <= a; z++){ // This allows each setting, ie. 1st, 4th, 7th AND 2nd, 5th, 8th to be tested
for (i = z; i < textL; i + a){
var string = '';
string = string.concat(text.charAt(i)); // Join each letter of the correct place in the string
stringtable[z] = indexofcoincidence(string);
}
}
hashtable[a] = stringtable.avg();
}
return hashtable;
}
Your problem is definitely right here
for (i = z; i < textL; i + a){
var string = '';
string = string.concat(text.charAt(i)); // Join each letter of the correct place in the string
stringtable[z] = indexofcoincidence(string);
}
Notice that if a=0 i never changes and therefore you are in an infinite loop.
Array.prototype.avg = function() {...}
should be only done once, and not every time keylengthfinder is called.
var Top = 0.027*textL;
var Bottom1 = 0.038*textL + 0.065;
var Bottom2 = (textL - 1)*Kappa;
var KeyLength = Top/(Bottom2 - Bottom1) ;
return Kappa/0.0385;
Why do you computer those variables if you don't use them at all?
var string = '';
string = string.concat(text.charAt(i)); // Join each letter of the correct place in the string
stringtable[z] = indexofcoincidence(string);
I don't know what you are trying to do in here. The string will always be only one character?
for (i = z; i < textL; i + a) {
...
stringtable[z] = ...
}
In this loop, you are computing values for i from z to textL - but you overwrite the same array item each time. So it would be enough to compute the stringtable[z] for i=textL-1 - or your algorithm is flawed.
A much shorter and more concise variant of the indexofcoincidence function:
function indexofcoincidence(text){
var l = text.replace(/ /g, "").length;
text = text.toUpperCase().replace(/[^A-Z]/g, "");
var hashtable = {};
for (var i=0; i<l; i++) {
var c = text.charAt(i);
hashtable[c] = (hashtable[c] || 0) + 1;
}
var kappa = 0;
for (var c in hashtable)
kappa += hashtable[c] * hashtable[c];
return kappa/(l*l)/0.0385;
}
All right. Now that we found your problem (including the infinite loop in case a=0, as detected by qw3n), let's rewrite the loop:
function keylengthfinder(text) {
var length = text.length,
probabilities = []; // probability by key length
maxkeylen = 13; // it might make more sense to determine this in relation to length
for (var a = 1; a <= maxkeylen; a++) { // testing each key length
var stringtable = Array(a); // strings to check with this gap
// read "a" as stringtable.length
for (var z = 0; z < a; z++) {
var string = '';
for (var i = z; i < textL; i += a) {
string += text.charAt(i);
}
// a string consisting of z, z+a, z+2a, z+3a, ... -th letters
stringtable[z] = string;
}
var sum = 0;
// summing up the coincidence indizes for current stringtable
for (var i=0; i<a; i++) {
sum += indexofcoincidence(stringtable[i]);
}
probabilities[a] = sum / a; // average
}
return probabilities;
}
Every of the loop statements has changed against your original script!
Never forget to declare the running variable to be local (var keyword)
a needs to start at zero - a key must have a minimum length of 1
to run from 1 to n, use i=1; i<=n; i++
to run from 0 to n-1, use i=0; i<n; i++ (nearly all loops, especially on zero-based array indizes).
Other loops than those two never occur in normal programs. You should get suspicious if you have loops from 0 to n or from 1 to n-1...
The update expression needs to update the running variable. i++ is a shortcut for i+=1 is a shortcut for i=i+1. Your expression, i + a, did not assign the new value (apart from the a=0 problem)!
I'm pretty new to programming and javascript/dom. Ultimately, I'm trying to make a sliding puzzle game but to start off with, I'm just trying to get the images loading up in a random order. It's going to be a 4x4 grid of images. The images are named Tree00, 01, 02, 03, 10, etc up to 33. Here's my code so far:
<html>
<head>
<title>Shuffle</title>
</head>
<body>
<script language="JavaScript">
<!--
Pics = new Array();
var Top = 16;
for(i = 0; i < Top; i++) {
document.write("<img><img><img><img><br>");
}
function RandomInt(Min, Max) {
RI = Math.floor(Math.random() * (Max - Min + 1)) + Min;
return(RI);
}
function Shuffle() {
N = RandomInt(0, 1);
this.Image.src=Pics[N];
this.Image.style.left = 220;
}
function ViewerObj(Image, Pics, i) {
this.Image = Image;
this.Image.style.left = 800;
this.Pics = Pics;
this.Shuffle = Shuffle;
this.Image.id = "ID" + i;
}
function Randomise() {
var i;
for(i = 0; i < Top; i++) {
Viewers[i].Shuffle();
Viewers[i].Image.style.left = 200;
}
}
Viewers = new Array();
var i;
for(i = 0; i < 3; i++) {
Pics[i] = "images/Tree" + (i) + (i + 1) + ".jpg";
}
for(i = 0; i < Top; i++) {
document.images[i].src = "images/Blank.jpg";
document.images[i].style.left = 300;
Viewers[i] = new ViewerObj(document.images[i], Pics, i);
}
//-->
</script>
<h1>Shuffle</h1>
<form>
<input type="button" value="Shuffle" onClick="Randomise();"/>
</form>
</body>
</html>
I just can't quite fathom what I need to be changing and how I'd go about it. Any help + explanation would be much appreciated. What I am trying to achieve is it loading every image but just in a random order, but with no duplicates.
Here are a few problems in your script :
first replace
for(i = 0; i < Top; i++) {
document.write("<img><img><img><img><br>");
}
by
for(i = 0; i < Top; i++) {
document.write("<img>");
if ((i+1)%4 == 0) {
document.write("<br>");
}
}
you will get only 16 IMG elements instead of 4*16 in your code
then you will need 16 different names for your images : replace
for(i = 0; i < 3; i++) {
Pics[i] = "images/Tree" + (i) + (i + 1) + ".jpg";
}
by
for(var i = 0; i < 4; i++) {
for(var j = 0; j < 4; j++) {
Pics[j+4*i] = "images/Tree" + (i) + (j) + ".jpg";
}
}
Then you biggest problem is the shuffling. You cannot shuffle the "Viewers" one-by-one because you want to avoid duplicates. Each viewer must randomly select a unique image.
For this you can use the technique in mdarwi's answer : shuffle the Pics table for instance.
check your modified code on jsbin here
If your problem is simply that you'd like the images to be properly shuffled, you can use the following code (taken directly from the Javascript sample code for the Fisher-Yates shuffle on Wikipedia:
var n = a.length;
for(var i = n - 1; i > 0; i--) {
var j = Math.floor(Math.random() * (i + 1));
var tmp = a[i];
a[i] = a[j];
a[j] = tmp;
}
The easiest thing to do would be to rename your images Tree1 to TreeN, and then place N integers in an array and shuffle them using the above algorithm.
(This is a code-comment, not an answer)
Pics = new Array();
The Pics variable should be declared before using. Also, use the shorthand notation []
var Pics = [];
var Top = 16;
for (i = 0; i < Top; i++) {
document.write("<img><img><img><img><br>");
}
The i variable is declared only later in the code. It should be declared at the top of the program.
function RandomInt(Min, Max) {
RI = Math.floor(Math.random() * (Max - Min + 1)) + Min;
return (RI);
}
This is particularly dangerous: the RI variable is not declared inside the function, so it becomes an implicit global property. That should be avoided. Also, the parens in the return statement are superfluous.
function RandomInt(Min, Max) {
return Math.floor(Math.random() * (Max - Min + 1)) + Min;
}
function Shuffle() {
N = RandomInt(0, 1);
this.Image.src = Pics[N];
this.Image.style.left = 220;
}
Again, the N variable should be declared. Also, why is this "method" declared outside of the ViewerObj constructor? Either, put it inside, or - even better - add it to the constructors prototype object. That way, there will only be one Shuffle function object instead of many.
function ViewerObj(Image, Pics, i) {
this.Image = Image;
this.Image.style.left = 800;
this.Pics = Pics;
this.Shuffle = Shuffle;
this.Image.id = "ID" + i;
}
function Randomise() {
var i;
for (i = 0; i < Top; i++) {
Viewers[i].Shuffle();
Viewers[i].Image.style.left = 200;
}
}
Viewers = new Array();
var i;
As mentioned above, the i variable should be declared on top. Also, the Viewers variable should be declared.
var Viewers = [];
for (i = 0; i < 3; i++) {
Pics[i] = "images/Tree" + (i) + (i + 1) + ".jpg";
}
for (i = 0; i < Top; i++) {
document.images[i].src = "images/Blank.jpg";
document.images[i].style.left = 300;
Viewers[i] = new ViewerObj(document.images[i], Pics, i);
}