JavaScript: Get all possible subset with a fixed length combinations in an array
JavaScript Function: Exercise-21 with Solution
Write a JavaScript function to get all possible subset with a fixed length (for example 2) combinations in an array.
Sample array : [1, 2, 3] and subset length is 2
Expected output : [[2, 1], [3, 1], [3, 2], [3, 2, 1]]
Sample Solution: -
HTML Code:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>JavaScript array subset</title>
</head>
<body>
</body>
</html>
JavaScript Code:
function subset(arra, arra_size)
{
var result_set = [],
result;
for(var x = 0; x < Math.pow(2, arra.length); x++)
{
result = [];
i = arra.length - 1;
do
{
if( (x & (1 << i)) !== 0)
{
result.push(arra[i]);
}
} while(i--);
if( result.length >= arra_size)
{
result_set.push(result);
}
}
return result_set;
}
console.log(subset([1, 2, 3], 2));
Sample Output:
[[2,1],[3,1],[3,2],[3,2,1]]
Flowchart:
Live Demo:
See the Pen JavaScript - Get all possible subset with a fixed length combinations in an array-function-ex- 21 by w3resource (@w3resource) on CodePen.
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JavaScript: Tips of the Day
How to insert an item into an array at a specific index (JavaScript)?
What you want is the splice function on the native array object.
arr.splice(index, 0, item); will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert). In this example we will create an array and add an element to it into index 2:
var arr = []; arr[0] = "Jani"; arr[1] = "Hege"; arr[2] = "Stale"; arr[3] = "Kai Jim"; arr[4] = "Borge"; console.log(arr.join()); arr.splice(2, 0, "Lene"); console.log(arr.join());
Ref: https://bit.ly/2BXbp04
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