I create this function in order to have a random number for my first dice game.
function rollDice() {
return Math.floor(Math.random()*6 + 1);
}
Now I want create a new function dices() with a for loop in order to use how much dices the user need.
Usually I used length in a loop as this example:
for (var i=1; i < dices.length; i++) {
// do something
}
How you got any suggestions on how to fix this?
Thank you!
I don't know if it's really what you're looking for, but you can simply create a function and replace dice.length by the number of time you want to roll, see this example:
function rollManyDice(number) {
var diceNumber = 0;
for (var i = 0; i < number; i++) {
diceNumber += rollDice();
}
return diceNumber;
}
Something like this function if I understand your question? It returns an array with the results from the number of dices thrown.
function throwDice(num) {
var arr = [];
for (var i = 0, l = num; i < l ; i++) {
arr.push(rolldice());
}
return arr;
}
throwDice(3); // e.g. [3, 5, 1]
function rollDice(sides, amount){
var results = [];
for (var i=0; i < amount; i++){
results.push( Math.floor(Math.random()*sides + 1) );
}
return results;
}
should return a array of how ever amount of dice with the specified number of sides.
Related
I need help with writing some code that will create a random number from an array of 12 numbers and print it 9 times without dupes. This has been tough for me to accomplish. Any ideas?
var nums = [1,2,3,4,5,6,7,8,9,10,11,12];
var gen_nums = [];
function in_array(array, el) {
for(var i = 0 ; i < array.length; i++)
if(array[i] == el) return true;
return false;
}
function get_rand(array) {
var rand = array[Math.floor(Math.random()*array.length)];
if(!in_array(gen_nums, rand)) {
gen_nums.push(rand);
return rand;
}
return get_rand(array);
}
for(var i = 0; i < 9; i++) {
console.log(get_rand(nums));
}
The most effective and efficient way to do this is to shuffle your numbers then print the first nine of them. Use a good shuffle algorithm.What Thilo suggested will give you poor results. See here.
Edit
Here's a brief Knuth Shuffle algorithm example:
void shuffle(vector<int> nums)
{
for (int i = nums.size()-1; i >= 0; i--)
{
// this line is really shorthand, but gets the point across, I hope.
swap(nums[i],nums[rand()%i]);
}
}
Try this once:
//Here o is the array;
var testArr = [6, 7, 12, 15, 17, 20, 21];
shuffle = function(o){ //v1.0
for(var j, x, i = o.length; i; j = parseInt(Math.random() * i), x = o[--i], o[i] = o[j], o[j] = x);
return o;
};
shuffle(testArr);
This is relatively simple to do, the theory behind it is creating another array which keeps track of which elements of the array you have used.
var tempArray = new Array(12),i,r;
for (i=0;i<9;i++)
{
r = Math.floor(Math.random()*12); // Get a random index
if (tempArray[r] === undefined) // If the index hasn't been used yet
{
document.write(numberArray[r]); // Display it
tempArray[r] = true; // Flag it as have been used
}
else // Otherwise
{
i--; // Try again
}
}
Other methods include shuffling the array, removing used elements from the array, or moving used elements to the end of the array.
If I understand you correctly, you want to shuffle your array.
Loop a couple of times (length of array should do), and in every iteration, get two random array indexes and swap the two elements there. (Update: if you are really serious about this, this may not be the best algorithm).
You can then print the first nine array elements, which will be in random order and not repeat.
Here is a generic way of getting random numbers between min and max without duplicates:
function inArray(arr, el) {
for(var i = 0 ; i < arr.length; i++)
if(arr[i] == el) return true;
return false;
}
function getRandomIntNoDuplicates(min, max, DuplicateArr) {
var RandomInt = Math.floor(Math.random() * (max - min + 1)) + min;
if (DuplicateArr.length > (max-min) ) return false; // break endless recursion
if(!inArray(DuplicateArr, RandomInt)) {
DuplicateArr.push(RandomInt);
return RandomInt;
}
return getRandomIntNoDuplicates(min, max, DuplicateArr); //recurse
}
call with:
var duplicates =[];
for (var i = 1; i <= 6 ; i++) {
console.log(getRandomIntNoDuplicates(1,10,duplicates));
}
const nums = [1,2,3,4,5,6,7,8,9,10,11,12];
for(var i = 1 ; i < 10; i++){
result = nums[Math.floor(Math.random()*nums.length)];
const index = nums.indexOf(result);
nums.splice(index, 1);
console.log(i+' - '+result);
}
I want the result to be the sum of every number, but instead, it only sums the first number with the rest. For example if the parameter were : 1,2,3,4,5
it should come out with 15 but instead, it became 3456. Where did i go wrong?
Thank u guys, i m new to this and thing were really complicated :((
function func1(sum) {
var result = '';
var i;
for (i = 1; i < arguments.length; i++) {
result += arguments[i] + sum;
}
return result;
}
Start with result being a number, not a string: var result = 0.
If you're iterating through arguments, you may as well skip the named first argument altogether.
Start iterating from 0, not 1.
function func1() {
var result = 0;
var i;
for (i = 0; i < arguments.length; i++) {
result += arguments[i];
}
return result;
}
console.log(func1(1, 2, 3, 4, 5));
This should work
function sum(value) {
let result = 0;
for(let i =0; i < value.length; i++) {
result +=value[i];
}
return result
}
let arry = [1,2,3,4,5]
console.log(sum(arry)) //15
I am trying to take a given array and iterate through it to create a new array containing only the numbers that are prime from the given array.
What I'm not sure of is the syntax for doing so - I know this is butchered and wrong, but I'm not sure how to fix it? Or if I'm even going about it the right way.
var myArray = isPrime([1,5,17,25,30])
console.log(myArray)
function isPrime(array){
var primes = [];
for(var i = 0; i < array.length; i++){
if(array[i] /= 1 || array[i] / 1 == array[i]){
primes.push([i]);
}
}
return primes;
}
A simple way to do it is creating a isElementPrime(number) function that tells if the number is prime or not (find an implementation here), and loop through it!
function isPrime(array){
var primes = [];
for(var i = 0; i < array.length; i++){
if(isElementPrime(array[i]){
primes.push(array[i]);
}
}
return primes;
}
The idea is to divide the number by every number smaller than it and greater than 1 and see if there is a remainder.
Using filter you can apply this to all elements in the array;
See example:
function isPrime(element) {
for(var i = 2; i < element; i++) {
if(element % i === 0) {
return false;
}
}
return element !== 1;
}
var array = [1, 5, 17, 25, 30];
var primes = array.filter(isPrime);
console.log("array: " + array);
console.log("primes: " + primes);
Very new, trying to make a function that takes out and separates all negatives/positives/zeros in an array. So far Ive been able to make an acceptable for loop but only with hard coded numbers. Dont currently know how to convert it into a function. please help.
var arr=[1,3,5,-9,-3,0];
var new_arr = [];
var new_arr2 = [];
var new_arr3=[];
for(i =0; i < arr.length; i++){
if(arr[i]>0){
new_arr.push(arr[i]);
}
else if(arr[i]<0){
new_arr2.push(arr[i]);
}
else if(arr[i]===0){
new_arr3.push(arr[i]);
}
}
console.log(new_arr3.length/arr.length);
console.log(new_arr2.length/arr.length);
console.log(new_arr.length/arr.length);
How about something like this?
function division(arr) {
var new_arr = [];
var new_arr2 = [];
var new_arr3 = [];
for (i = 0; i < arr.length; i++) {
if (arr[i] > 0) {
new_arr.push(arr[i]);
} else if (arr[i] < 0) {
new_arr2.push(arr[i]);
} else if (arr[i] === 0) {
new_arr3.push(arr[i]);
}
}
console.log(new_arr3.length / arr.length);
console.log(new_arr2.length / arr.length);
console.log(new_arr.length / arr.length);
}
division([1, 3, 5, -9, -3, 0]);
This new function takes the array as a parameter, so all you need to do is call it and pass the array.
You can try this way also, here I am considering 0 as a positive number. If you want, you can tweak the condition as per requirement.
function positive_negative(array ){
positive = array.filter(function (a) { return a >= 0; });
negative = array.filter(function (a) { return a < 0; });
return [positive,negative];
}
var array = [1,3,5,-9,-3,0];
console.log(positive_negative(array));
I need help with writing some code that will create a random number from an array of 12 numbers and print it 9 times without dupes. This has been tough for me to accomplish. Any ideas?
var nums = [1,2,3,4,5,6,7,8,9,10,11,12];
var gen_nums = [];
function in_array(array, el) {
for(var i = 0 ; i < array.length; i++)
if(array[i] == el) return true;
return false;
}
function get_rand(array) {
var rand = array[Math.floor(Math.random()*array.length)];
if(!in_array(gen_nums, rand)) {
gen_nums.push(rand);
return rand;
}
return get_rand(array);
}
for(var i = 0; i < 9; i++) {
console.log(get_rand(nums));
}
The most effective and efficient way to do this is to shuffle your numbers then print the first nine of them. Use a good shuffle algorithm.What Thilo suggested will give you poor results. See here.
Edit
Here's a brief Knuth Shuffle algorithm example:
void shuffle(vector<int> nums)
{
for (int i = nums.size()-1; i >= 0; i--)
{
// this line is really shorthand, but gets the point across, I hope.
swap(nums[i],nums[rand()%i]);
}
}
Try this once:
//Here o is the array;
var testArr = [6, 7, 12, 15, 17, 20, 21];
shuffle = function(o){ //v1.0
for(var j, x, i = o.length; i; j = parseInt(Math.random() * i), x = o[--i], o[i] = o[j], o[j] = x);
return o;
};
shuffle(testArr);
This is relatively simple to do, the theory behind it is creating another array which keeps track of which elements of the array you have used.
var tempArray = new Array(12),i,r;
for (i=0;i<9;i++)
{
r = Math.floor(Math.random()*12); // Get a random index
if (tempArray[r] === undefined) // If the index hasn't been used yet
{
document.write(numberArray[r]); // Display it
tempArray[r] = true; // Flag it as have been used
}
else // Otherwise
{
i--; // Try again
}
}
Other methods include shuffling the array, removing used elements from the array, or moving used elements to the end of the array.
If I understand you correctly, you want to shuffle your array.
Loop a couple of times (length of array should do), and in every iteration, get two random array indexes and swap the two elements there. (Update: if you are really serious about this, this may not be the best algorithm).
You can then print the first nine array elements, which will be in random order and not repeat.
Here is a generic way of getting random numbers between min and max without duplicates:
function inArray(arr, el) {
for(var i = 0 ; i < arr.length; i++)
if(arr[i] == el) return true;
return false;
}
function getRandomIntNoDuplicates(min, max, DuplicateArr) {
var RandomInt = Math.floor(Math.random() * (max - min + 1)) + min;
if (DuplicateArr.length > (max-min) ) return false; // break endless recursion
if(!inArray(DuplicateArr, RandomInt)) {
DuplicateArr.push(RandomInt);
return RandomInt;
}
return getRandomIntNoDuplicates(min, max, DuplicateArr); //recurse
}
call with:
var duplicates =[];
for (var i = 1; i <= 6 ; i++) {
console.log(getRandomIntNoDuplicates(1,10,duplicates));
}
const nums = [1,2,3,4,5,6,7,8,9,10,11,12];
for(var i = 1 ; i < 10; i++){
result = nums[Math.floor(Math.random()*nums.length)];
const index = nums.indexOf(result);
nums.splice(index, 1);
console.log(i+' - '+result);
}