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I am trying to write a program in javascript that gets an unspecified number of numbers out of a html textarea and tries all binations (adding all numbers with eachother) to see if it mathches a number you specified.
Now I can make an array out of the string in the textarea and using for loops I add these up (see below code). The problem how can you do this for an unspecified number of numbers that are to be added up (e.g. adding up 7 different number if you enter 7 numbers in textarea)? I was thinking of using a second array and, which gets the numbers to add up out of the first loop. And then make te lenght of the loop variable by using a for loop with the lenght of the array containing all numbers (lines in my example) as endvalue.
How can I fill in the values of this 2nd array, making sure all binations are used?
By the way, I wanted this code because I am a auditor. Sometimes a client reverses a couple of amounts in one booking, without any ment. This code will make it a lot easier to check what bookings have been reversed
edit: The awnser of cheeken seems to be working I only have one remark. What if multiple sub sets of your power set added up result in the number you are looking for? e.g.:findSum([1,2,3,4,5],6) can result [1,2,3] but also [2,4] or [1,5]. is it possible to let the function return multiple sub sets?
Found the answer my self :) I replaced code
return numberSet;
By
document.getElementById("outp").value=document.getElementById("outp").value+ numberSet +"\n";
Thank you very much Cheeken
One more additional question. How do i format the input for parsing that function? The code below doesn't seem to work. inp is the ID of the textarea where the input is (the numbers are seperated with a semicolumn. The variable ge works so there is no problem there (tested it with [1,2,3,4] and it worked. What is wrong with this code?
re edit:
found the solution. The array needed to be parsed as a floating number added this code.`
for (var i=0; i < lines.length; i++) {
lines[i]= parseFloat(lines[i]);
}
findSum(document.getElementById("inp").value.split(";"), ge);
Code:
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript">
function powerset(arr) {
var ps = [[]];
for (var i=0; i < arr.length; i++) {
for (var j = 0, len = ps.length; j < len; j++) {
ps.push(ps[j].concat(arr[i]));
}
}
return ps;
}
function sum(arr) {
var total = 0;
for (var i = 0; i < arr.length; i++)
total += arr[i];
return total
}
function findSum(numbers, targetSum) {
var numberSets = powerset(numbers);
for (var i=0; i < numberSets.length; i++) {
var numberSet = numberSets[i];
if (sum(numberSet) == targetSum)
document.getElementById("outp").value=document.getElementById("outp").value+ numberSet +"\n";
}
}
function main()
{
ge= document.getElementById("getal").value;
findSum([1,1,0.5,0.1,0.2,0.2], ge);
}
</script>
</head>
<body>
<input type="button" onclick="main()" value="tel" /><input type="text" id="getal" /><br>
input<br><textarea id="inp" ></textarea><br>
output<br><textarea id="outp" ></textarea><br>
document.getElementById("inp").value.split(";")
</body>
</html>
I am trying to write a program in javascript that gets an unspecified number of numbers out of a html textarea and tries all binations (adding all numbers with eachother) to see if it mathches a number you specified.
Now I can make an array out of the string in the textarea and using for loops I add these up (see below code). The problem how can you do this for an unspecified number of numbers that are to be added up (e.g. adding up 7 different number if you enter 7 numbers in textarea)? I was thinking of using a second array and, which gets the numbers to add up out of the first loop. And then make te lenght of the loop variable by using a for loop with the lenght of the array containing all numbers (lines in my example) as endvalue.
How can I fill in the values of this 2nd array, making sure all binations are used?
By the way, I wanted this code because I am a auditor. Sometimes a client reverses a couple of amounts in one booking, without any ment. This code will make it a lot easier to check what bookings have been reversed
edit: The awnser of cheeken seems to be working I only have one remark. What if multiple sub sets of your power set added up result in the number you are looking for? e.g.:findSum([1,2,3,4,5],6) can result [1,2,3] but also [2,4] or [1,5]. is it possible to let the function return multiple sub sets?
Found the answer my self :) I replaced code
return numberSet;
By
document.getElementById("outp").value=document.getElementById("outp").value+ numberSet +"\n";
Thank you very much Cheeken
One more additional question. How do i format the input for parsing that function? The code below doesn't seem to work. inp is the ID of the textarea where the input is (the numbers are seperated with a semicolumn. The variable ge works so there is no problem there (tested it with [1,2,3,4] and it worked. What is wrong with this code?
re edit:
found the solution. The array needed to be parsed as a floating number added this code.`
for (var i=0; i < lines.length; i++) {
lines[i]= parseFloat(lines[i]);
}
findSum(document.getElementById("inp").value.split(";"), ge);
Code:
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript">
function powerset(arr) {
var ps = [[]];
for (var i=0; i < arr.length; i++) {
for (var j = 0, len = ps.length; j < len; j++) {
ps.push(ps[j].concat(arr[i]));
}
}
return ps;
}
function sum(arr) {
var total = 0;
for (var i = 0; i < arr.length; i++)
total += arr[i];
return total
}
function findSum(numbers, targetSum) {
var numberSets = powerset(numbers);
for (var i=0; i < numberSets.length; i++) {
var numberSet = numberSets[i];
if (sum(numberSet) == targetSum)
document.getElementById("outp").value=document.getElementById("outp").value+ numberSet +"\n";
}
}
function main()
{
ge= document.getElementById("getal").value;
findSum([1,1,0.5,0.1,0.2,0.2], ge);
}
</script>
</head>
<body>
<input type="button" onclick="main()" value="tel" /><input type="text" id="getal" /><br>
input<br><textarea id="inp" ></textarea><br>
output<br><textarea id="outp" ></textarea><br>
document.getElementById("inp").value.split(";")
</body>
</html>
- Homework questions should be tagged as homework. Please edit/update the tags on your question. – Incognito Commented Aug 18, 2012 at 16:03
- 2 This is not homework as explained below. ;) – Pieterjan Van Dam Commented Aug 18, 2012 at 16:58
- Can no one explain to me how it es document.getElementById("inp").value.split(";") cqn't be used as a parameter? I have also tried defining the array fist://lines = [[]]; lines = document.getElementById("inp").value.split(",");// using lines as parameter – Pieterjan Van Dam Commented Aug 19, 2012 at 10:43
- Ok. I found the answer to my previous ment. Thanks again for the support Cheeken :) – Pieterjan Van Dam Commented Aug 19, 2012 at 10:51
1 Answer
Reset to default 13More concretely, you're looking for a particular sum of each set in the power set of your collection of numbers.
You can acplish this with the following bit of code.
function powerset(arr) {
var ps = [[]];
for (var i=0; i < arr.length; i++) {
for (var j = 0, len = ps.length; j < len; j++) {
ps.push(ps[j].concat(arr[i]));
}
}
return ps;
}
function sum(arr) {
var total = 0;
for (var i = 0; i < arr.length; i++)
total += arr[i];
return total
}
function findSum(numbers, targetSum) {
var numberSets = powerset(numbers);
for (var i=0; i < numberSets.length; i++) {
var numberSet = numberSets[i];
if (sum(numberSet) == targetSum)
return numberSet;
}
}
Example invocation:
>> findSum([1,2,3,4,5],6)
[1, 2, 3]
>> findSum([1,2,3,4,5],0)
[]
>> findSum([1,2,3,4,5],11)
[1, 2, 3, 5]
If you'd like to collect all of the subsets whose sum is the value (rather than the first one, as implemented above) you can use the following method.
function findSums(numbers, targetSum) {
var sumSets = [];
var numberSets = powerset(numbers);
for (var i=0; i < numberSets.length; i++) {
var numberSet = numberSets[i];
if (sum(numberSet) == targetSum)
sumSets.push(numberSet);
}
return sumSets;
}
Example invocation:
>> findSums([1,2,3,4,5],5);
[[2,3],[1,4],[5]]
>> findSums([1,2,3,4,5],0);
[[]]
本文标签： javascriptAdding up all combinations of number in an arrayStack Overflow
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