Find all subarray with sum equal to number?

This might not be exactly what's needed - might require tweaking as the logic may be flawed here.

I have commented the code for clarification.

var arr = [1, 3, 6, 11, 1, 5,4];	//  Define array

var target = 31;	//  Define target

//  filter the numbers higher than target and sort rest ascending
var withinRange = arr.filter(x => x <= target).sort((a, b) => a - b);
                      
if(arr.reduce((a,b) => a + b) < target)	//  Check if we have enough numbers to make up that number
  throw "The max you can get out of your selection is: " + arr.reduce((a,b) => a + b);
                      
//  grab the highest number as a starting point and remove it from our array of numbers
var numbers = [withinRange.pop()];

var toFind = target - getSum();	//  get remainder to find

for(var i = withinRange.length - 1; i > -1; i--)	//  iterate from the top
{

  if(toFind == withinRange[i]){	//  check if number is exactly what we need
    numbers.push(withinRange[i]);
    break;
  }else if(withinRange[i] <= toFind){	//  if number is smaller than what we look for
    numbers.push(withinRange[i]);
    toFind -= withinRange[i];
  }

}

function getSum(){	//  sum up our found numbers
  if(numbers.length == 0) return 0;
  return numbers.reduce((a,b) => a + b);
}

console.log([numbers, [target]]);	//  print numbers as desired output
console.log(target, getSum())	//  print the target and our numbers

function combinations(array) {
    return new Array(1 << array.length).fill().map(
        (e1,i) => array.filter((e2, j) => i & 1 << j));
}

function add(acc,a) {
  return acc + a 
}

combinations([2, 4, 45, 6, 0, 19]).filter( subarray => subarray.reduce(add, 0)  == 51 )

output

[[2,4,45],[45,6],[2,4,45,0],[45,6,0]]

combinations([1, 11, 100, 1, 0, 200, 3, 2, 1, 280]).filter( subarray => subarray.reduce(add, 0)  == 280 )

output

[[280],[0,280]]

You could iterate the array and take either the next element or if no element is taken before omit this element.

function getSubset(array, sum) {
    function iter(temp, delta, index) {
        if (!delta) result.push(temp);
        if (index >= array.length) return;
        iter(temp.concat(array[index]), delta - array[index], index + 1);
        if (!temp.length) iter(temp, delta, index + 1);
    }

    var result = [];
    iter([], sum, 0);
    return result;
}

console.log(getSubset([2, 4, 45, 6, 0, 19], 51));                   // [2, 4, 45], [45, 6], [45, 6, 0]
console.log(getSubset([1, 11, 100, 1, 0, 200, 3, 2, 1, 280], 280)); // [280]
console.log(getSubset([1, 3, 6, 11, 1, 5, 4], 4));                  // [1, 3], [4]

Tags:

Javascript

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