I have to make a pattern like this:
=========1=========
=======22122=======
====33322122333====
4444333221223334444
I have not found the logic yet. I tried to code it, but the output is different.
Here is the output of my working code snippet:
----1-----
---123----
--12345---
-1234567--
123456789-
function nomor3(input){
let temp = '';
for (let x = 1; x <= input; x++){
for (let y = input ; y > x; y--){
temp += "-";
}
for (let z = 1; z <= (x * 2) - 1; z++){
temp += z;
}
for (let k = input; k >= x; k--){
temp += "-";
}
temp += '\n';
}
return temp
}
console.log(nomor3(5));
The logic for each level - say 4th level - it begins with the digit of the level to the count of the digit, then one less and so on. So line 4 looks like 4444-333-22-1 and backwards (dashes added for demonstration).
So here we build each line like that, starting from the biggest so we know its length so we can center other lines with dashes. We use arrays here and reversing them because it's easier than strings. But lastly we join so we have a string.
function pyramide(level) {
var len = null;
var result = [];
while (level > 0) {
var arr = [];
for (var i = level; i > 1; i--) {
for (var repeat = 0; repeat < i; repeat++) {
arr.push(i)
}
}
var str_level = arr.join("") + "1" + arr.reverse().join("");
if (len === null) {
len = str_level.length;
}
while (str_level.length < len) {
str_level = "-" + str_level + "-";
}
result.push(str_level);
level--;
}
return result.reverse().join("\n");
}
console.log(pyramide(5))
What I want to do is encrypt a string with this formula after making it lowercase and removing all the spaces: C_n = P_(n–1) * P_n + P_(n+1)
How do I go about doing this in JS?
assuming assignments for a=1, b=2, .. and that position wraps (meaning pos(-1) = 3 for a 4 letter word).
function encrypt(str) {
str = str.toLowerCase().replace(/[^a-z]/, '');
var len = str.length() - 1;
var P = (n) => {
if (n < 0) n = n+len;
if (n >= len) n = n-len;
return str.charCodeAt(n) - 64;
}
var result = '';
for (var n = 0; n < len, n++) {
var c = P(n-1) * P(n) + P(n+1);
result += String.fromCharCode(c);
}
return result;
}
how can i compare the first and last / second and second last elements of the string in java script
ex: we take in 102201
compare 1 and 1
0 and 0
2 and 2
it's want to any string.
if another ex: element
then
check e and t
l and n
e and e
m forgot it.
my code like
function check() {
var input = document.getElementById("check").value;
var inputcount = "";
if ((input.length) % 2 === 0) {
inputcount = (input.length) / 2;
} else {
inputcount = (input.length - 1) / 2;
}
for (var x = 0; x < inputcount; x++) {
//....
}
}
You can subtract the x from the array length to get the last character
function check() {
var input = document.getElementById("check").value;
var inputcount = Math.floor(input.length / 2);
for (var x = 0; x < inputcount; x++) {
snippet.log(input[x] + ' and ' + input[input.length - x - 1])
}
}
<script src="http://tjcrowder.github.io/simple-snippets-console/snippet.js"></script>
<input id="check" onchange="check()" />
So I have a random javascript array of names...
[#larry,#nicholas,#notch] etc.
They all start with the # symbol. I'd like to sort them by the Levenshtein Distance so that the the ones at the top of the list are closest to the search term. At the moment, I have some javascript that uses jQuery's .grep() on it using javascript .match() method around the entered search term on key press:
(code edited since first publish)
limitArr = $.grep(imTheCallback, function(n){
return n.match(searchy.toLowerCase())
});
modArr = limitArr.sort(levenshtein(searchy.toLowerCase(), 50))
if (modArr[0].substr(0, 1) == '#') {
if (atRes.childred('div').length < 6) {
modArr.forEach(function(i){
atRes.append('<div class="oneResult">' + i + '</div>');
});
}
} else if (modArr[0].substr(0, 1) == '#') {
if (tagRes.children('div').length < 6) {
modArr.forEach(function(i){
tagRes.append('<div class="oneResult">' + i + '</div>');
});
}
}
$('.oneResult:first-child').addClass('active');
$('.oneResult').click(function(){
window.location.href = 'http://hashtag.ly/' + $(this).html();
});
It also has some if statements detecting if the array contains hashtags (#) or mentions (#). Ignore that. The imTheCallback is the array of names, either hashtags or mentions, then modArr is the array sorted. Then the .atResults and .tagResults elements are the elements that it appends each time in the array to, this forms a list of names based on the entered search terms.
I also have the Levenshtein Distance algorithm:
var levenshtein = function(min, split) {
// Levenshtein Algorithm Revisited - WebReflection
try {
split = !("0")[0]
} catch(i) {
split = true
};
return function(a, b) {
if (a == b)
return 0;
if (!a.length || !b.length)
return b.length || a.length;
if (split) {
a = a.split("");
b = b.split("")
};
var len1 = a.length + 1,
len2 = b.length + 1,
I = 0,
i = 0,
d = [[0]],
c, j, J;
while (++i < len2)
d[0][i] = i;
i = 0;
while (++i < len1) {
J = j = 0;
c = a[I];
d[i] = [i];
while(++j < len2) {
d[i][j] = min(d[I][j] + 1, d[i][J] + 1, d[I][J] + (c != b[J]));
++J;
};
++I;
};
return d[len1 - 1][len2 - 1];
}
}(Math.min, false);
How can I work with algorithm (or a similar one) into my current code to sort it without bad performance?
UPDATE:
So I'm now using James Westgate's Lev Dist function. Works WAYYYY fast. So performance is solved, the issue now is using it with source...
modArr = limitArr.sort(function(a, b){
levDist(a, searchy)
levDist(b, searchy)
});
My problem now is general understanding on using the .sort() method. Help is appreciated, thanks.
Thanks!
I wrote an inline spell checker a few years ago and implemented a Levenshtein algorithm - since it was inline and for IE8 I did quite a lot of performance optimisation.
var levDist = function(s, t) {
var d = []; //2d matrix
// Step 1
var n = s.length;
var m = t.length;
if (n == 0) return m;
if (m == 0) return n;
//Create an array of arrays in javascript (a descending loop is quicker)
for (var i = n; i >= 0; i--) d[i] = [];
// Step 2
for (var i = n; i >= 0; i--) d[i][0] = i;
for (var j = m; j >= 0; j--) d[0][j] = j;
// Step 3
for (var i = 1; i <= n; i++) {
var s_i = s.charAt(i - 1);
// Step 4
for (var j = 1; j <= m; j++) {
//Check the jagged ld total so far
if (i == j && d[i][j] > 4) return n;
var t_j = t.charAt(j - 1);
var cost = (s_i == t_j) ? 0 : 1; // Step 5
//Calculate the minimum
var mi = d[i - 1][j] + 1;
var b = d[i][j - 1] + 1;
var c = d[i - 1][j - 1] + cost;
if (b < mi) mi = b;
if (c < mi) mi = c;
d[i][j] = mi; // Step 6
//Damerau transposition
if (i > 1 && j > 1 && s_i == t.charAt(j - 2) && s.charAt(i - 2) == t_j) {
d[i][j] = Math.min(d[i][j], d[i - 2][j - 2] + cost);
}
}
}
// Step 7
return d[n][m];
}
I came to this solution:
var levenshtein = (function() {
var row2 = [];
return function(s1, s2) {
if (s1 === s2) {
return 0;
} else {
var s1_len = s1.length, s2_len = s2.length;
if (s1_len && s2_len) {
var i1 = 0, i2 = 0, a, b, c, c2, row = row2;
while (i1 < s1_len)
row[i1] = ++i1;
while (i2 < s2_len) {
c2 = s2.charCodeAt(i2);
a = i2;
++i2;
b = i2;
for (i1 = 0; i1 < s1_len; ++i1) {
c = a + (s1.charCodeAt(i1) === c2 ? 0 : 1);
a = row[i1];
b = b < a ? (b < c ? b + 1 : c) : (a < c ? a + 1 : c);
row[i1] = b;
}
}
return b;
} else {
return s1_len + s2_len;
}
}
};
})();
See also http://jsperf.com/levenshtein-distance/12
Most speed was gained by eliminating some array usages.
Updated: http://jsperf.com/levenshtein-distance/5
The new Revision annihilates all other benchmarks. I was specifically chasing Chromium/Firefox performance as I don't have an IE8/9/10 test environment, but the optimisations made should apply in general to most browsers.
Levenshtein Distance
The matrix to perform Levenshtein Distance can be reused again and again. This was an obvious target for optimisation (but be careful, this now imposes a limit on string length (unless you were to resize the matrix dynamically)).
The only option for optimisation not pursued in jsPerf Revision 5 is memoisation. Depending on your use of Levenshtein Distance, this could help drastically but was omitted due to its implementation specific nature.
// Cache the matrix. Note this implementation is limited to
// strings of 64 char or less. This could be altered to update
// dynamically, or a larger value could be used.
var matrix = [];
for (var i = 0; i < 64; i++) {
matrix[i] = [i];
matrix[i].length = 64;
}
for (var i = 0; i < 64; i++) {
matrix[0][i] = i;
}
// Functional implementation of Levenshtein Distance.
String.levenshteinDistance = function(__this, that, limit) {
var thisLength = __this.length, thatLength = that.length;
if (Math.abs(thisLength - thatLength) > (limit || 32)) return limit || 32;
if (thisLength === 0) return thatLength;
if (thatLength === 0) return thisLength;
// Calculate matrix.
var this_i, that_j, cost, min, t;
for (i = 1; i <= thisLength; ++i) {
this_i = __this[i-1];
for (j = 1; j <= thatLength; ++j) {
// Check the jagged ld total so far
if (i === j && matrix[i][j] > 4) return thisLength;
that_j = that[j-1];
cost = (this_i === that_j) ? 0 : 1; // Chars already match, no ++op to count.
// Calculate the minimum (much faster than Math.min(...)).
min = matrix[i - 1][j ] + 1; // Deletion.
if ((t = matrix[i ][j - 1] + 1 ) < min) min = t; // Insertion.
if ((t = matrix[i - 1][j - 1] + cost) < min) min = t; // Substitution.
matrix[i][j] = min; // Update matrix.
}
}
return matrix[thisLength][thatLength];
};
Damerau-Levenshtein Distance
jsperf.com/damerau-levenshtein-distance
Damerau-Levenshtein Distance is a small modification to Levenshtein Distance to include transpositions. There is very little to optimise.
// Damerau transposition.
if (i > 1 && j > 1 && this_i === that[j-2] && this[i-2] === that_j
&& (t = matrix[i-2][j-2]+cost) < matrix[i][j]) matrix[i][j] = t;
Sorting Algorithm
The second part of this answer is to choose an appropriate sort function. I will upload optimised sort functions to http://jsperf.com/sort soon.
I implemented a very performant implementation of levenshtein distance calculation if you still need this.
function levenshtein(s, t) {
if (s === t) {
return 0;
}
var n = s.length, m = t.length;
if (n === 0 || m === 0) {
return n + m;
}
var x = 0, y, a, b, c, d, g, h, k;
var p = new Array(n);
for (y = 0; y < n;) {
p[y] = ++y;
}
for (; (x + 3) < m; x += 4) {
var e1 = t.charCodeAt(x);
var e2 = t.charCodeAt(x + 1);
var e3 = t.charCodeAt(x + 2);
var e4 = t.charCodeAt(x + 3);
c = x;
b = x + 1;
d = x + 2;
g = x + 3;
h = x + 4;
for (y = 0; y < n; y++) {
k = s.charCodeAt(y);
a = p[y];
if (a < c || b < c) {
c = (a > b ? b + 1 : a + 1);
}
else {
if (e1 !== k) {
c++;
}
}
if (c < b || d < b) {
b = (c > d ? d + 1 : c + 1);
}
else {
if (e2 !== k) {
b++;
}
}
if (b < d || g < d) {
d = (b > g ? g + 1 : b + 1);
}
else {
if (e3 !== k) {
d++;
}
}
if (d < g || h < g) {
g = (d > h ? h + 1 : d + 1);
}
else {
if (e4 !== k) {
g++;
}
}
p[y] = h = g;
g = d;
d = b;
b = c;
c = a;
}
}
for (; x < m;) {
var e = t.charCodeAt(x);
c = x;
d = ++x;
for (y = 0; y < n; y++) {
a = p[y];
if (a < c || d < c) {
d = (a > d ? d + 1 : a + 1);
}
else {
if (e !== s.charCodeAt(y)) {
d = c + 1;
}
else {
d = c;
}
}
p[y] = d;
c = a;
}
h = d;
}
return h;
}
It was my answer to a similar SO question
Fastest general purpose Levenshtein Javascript implementation
Update
A improved version of the above is now on github/npm see
https://github.com/gustf/js-levenshtein
The obvious way of doing this is to map each string to a (distance, string) pair, then sort this list, then drop the distances again. This way you ensure the levenstein distance only has to be computed once. Maybe merge duplicates first, too.
I would definitely suggest using a better Levenshtein method like the one in #James Westgate's answer.
That said, DOM manipulations are often a great expense. You can certainly improve your jQuery usage.
Your loops are rather small in the example above, but concatenating the generated html for each oneResult into a single string and doing one append at the end of the loop will be much more efficient.
Your selectors are slow. $('.oneResult') will search all elements in the DOM and test their className in older IE browsers. You may want to consider something like atRes.find('.oneResult') to scope the search.
In the case of adding the click handlers, we may want to do one better avoid setting handlers on every keyup. You could leverage event delegation by setting a single handler on atRest for all results in the same block you are setting the keyup handler:
atRest.on('click', '.oneResult', function(){
window.location.href = 'http://hashtag.ly/' + $(this).html();
});
See http://api.jquery.com/on/ for more info.
I just wrote an new revision: http://jsperf.com/levenshtein-algorithms/16
function levenshtein(a, b) {
if (a === b) return 0;
var aLen = a.length;
var bLen = b.length;
if (0 === aLen) return bLen;
if (0 === bLen) return aLen;
var len = aLen + 1;
var v0 = new Array(len);
var v1 = new Array(len);
var i = 0;
var j = 0;
var c2, min, tmp;
while (i < len) v0[i] = i++;
while (j < bLen) {
c2 = b.charAt(j++);
v1[0] = j;
i = 0;
while (i < aLen) {
min = v0[i] - (a.charAt(i) === c2 ? 1 : 0);
if (v1[i] < min) min = v1[i];
if (v0[++i] < min) min = v0[i];
v1[i] = min + 1;
}
tmp = v0;
v0 = v1;
v1 = tmp;
}
return v0[aLen];
}
This revision is faster than the other ones. Works even on IE =)
How can I check for matching numbers in this script, stuck here, I need to compare the array of user numbers with the array of lotto numbers and display how many numbers they got correct if any along with their prize value.
function numbers() {
var numbercount = 6;
var maxnumbers = 40;
var ok = 1;
r = new Array(numbercount);
for (var i = 1; i <= numbercount; i++) {
r[i] = Math.round(Math.random() * (maxnumbers - 1)) + 1;
}
for (var i = numbercount; i >= 1; i--) {
for (var j = numbercount; j >= 1; j--) {
if ((i != j) && (r[i] == r[j])) ok = 0;
}
}
if (ok) {
var output = "";
for (var k = 1; k <= numbercount; k++) {
output += r[k] + ", ";
}
document.lotto.results.value = output;
} else numbers();
}
function userNumbers() {
var usersNumbers = new Array(5);
for (var count = 0; count <= 5; count++) {
usersNumbers[count] = window.prompt("Enter your number " + (count + 1) + ": ");
}
document.lotto.usersNumbers.value = usersNumbers;
}
Here is a lotto numbers generator and a scoring system. I'm going to leave it to you to validate the user input.
function lottoGen(){
var lottoNumbers = [];
for(var k = 0; k<6; k++){
var num = Math.floor(Math.random()*41);
if(lottoNumbers.indexOf(num) != -1){
lottoNumbers.push(num);
}
}
return lottoNumbers;
}
function scoreIt(){
var usersNumbers = document.getElementsByName('usersNumbers').item(0);
usersNumbers = String(usersNumbers)
usersNumbers = usersNumbers.split(' ');
var matches = 0;
for(var i = 0; i<6; i++){
if(lottoNumbers.indexOf(usersNumbers[i]) != -1){matches++;}
}
return matches;
}
Hi I'm new to this and trying to learn off my own back so obviously I'm no expert but the code above makes a lot of sense to me, apart from the fact I can't get it to work.. I tried to console.log where it says RETURN so I could see the numbers but it just shows an empty array still. I assumed this was to do with it being outside the loop..
I've tried various ways but the best I get is an array that loops the same number or an array with 6 numbers but some of which are repeated..
function lottoGen(){
var lottoNumbers = [];
for(var k = 0; k<6; k++){
var num = Math.floor(Math.random()*41);
if(lottoNumbers.indexOf(num) != -1){
lottoNumbers.push(num);
}
}
return lottoNumbers;
}
Lotto JS: CODEPEN DEMO >> HERE <<
(function(){
var btn = document.querySelector("button");
var output = document.querySelector("#result");
function getRandom(min, max){
return Math.round(Math.random() * (max - min) + min);
}
function showRandomNUmbers(){
var numbers = [],
random;
for(var i = 0; i < 6; i++){
random = getRandom(1, 49);
while(numbers.indexOf(random) !== -1){
console.log("upps (" + random + ") it is in already.");
random = getRandom(1, 49);
console.log("replaced with: (" + random + ").");
}
numbers.push(random);
}
output.value = numbers.join(", ");
}
btn.onclick = showRandomNUmbers;
})();