Finding the sum of values of objects within arrays using recursion

Question

I am trying to get the sum of tasks completed using recursion. An object represents a team member and they can manage other members.

var team = {
  name: 'Rufus',
  completedTasks: 4,
  manages: [
    {
      name: 'Clara',
      completedTasks: 6,
      manages: [
        {
          name: 'Dana',
          completedTasks: 12,
          manages: []
        }
      ]
    },
   {
      name: 'Charles',
      completedTasks: 19,
      manages: []
    }
  ]
};

This is what I have implemented, but I am not getting 41. 4 + 6 + 12 + 19 = 41. The function is returning 45.

var totalTasks = function (team) {
  
  var sum = 0;
  
  var innerFunction = function(obj) {

  if (obj.manages.length === 0) {
    sum += obj.completedTasks;
    return;
  }

    obj.manages.forEach(function(item) {
      sum += obj.completedTasks;
      innerFunction(item);
    });
  };

  innerFunction(team);

  return sum;
};

totalTasks(team);

trincot · Accepted Answer · 2021-09-24 06:08:17Z

This happens because in your forEach loop you add obj.completedTasks which has nothing to do with the looped item, and so you are adding the same number in every iteration.

Keep the adding limited to only add obj.completedTasks once (as the first thing to do), unconditionally. So:

var team = {name: 'Rufus',completedTasks: 4,manages: [{name: 'Clara',completedTasks: 6,manages: [{name: 'Dana',completedTasks: 12,manages: []}]},{name: 'Charles',completedTasks: 19,manages: []}]};

var totalTasks = function (team) {
  var sum = 0;

  var innerFunction = function(obj) {
    sum += obj.completedTasks;
    if (obj.manages.length === 0) return;
    obj.manages.forEach(innerFunction);
  };

  innerFunction(team);
  return sum;
};

console.log(totalTasks(team));

It is nicer if you don't manage sum as a non-local variable, but just accumulate it recursively:

var team = {name: 'Rufus',completedTasks: 4,manages: [{name: 'Clara',completedTasks: 6,manages: [{name: 'Dana',completedTasks: 12,manages: []}]},{name: 'Charles',completedTasks: 19,manages: []}]};

var totalTasks = team =>
    team.completedTasks + 
    team.manages.reduce((sum, child) => sum + totalTasks(child), 0);

console.log(totalTasks(team));

trinalbadger587 · Accepted Answer · 2021-09-24 06:08:24Z

The problem with your code is that you wrote:

sum += obj.completedTasks;

instead of

sum += item.completedTasks;

inside the foreach which means that the outer person's completed tasks is getting added instead of the inner person's.

Regardless, it seemed your function was overcomplicated and could be shortened.

function allTasks (person)
{
    return person.completedTasks + person.manages.map(allTasks).reduce((a, b) => a + b, 0);
}

var team = {
  name: 'Rufus',
  completedTasks: 4,
  manages: [
    {
      name: 'Clara',
      completedTasks: 6,
      manages: [
        {
          name: 'Dana',
          completedTasks: 12,
          manages: []
        }
      ]
    },
   {
      name: 'Charles',
      completedTasks: 19,
      manages: []
    }
  ]
};

function allTasks (person)
{
    return person.completedTasks + person.manages.map(allTasks).reduce((a, b) => a + b, 0);
}

console.log(allTasks(team));

Kuncheria · Accepted Answer · 2021-09-24 06:17:47Z

0

The following code will solve the problem.

function totalTasks(item){
  if (item.manages.length){
    return item.completedTasks + item.manages.reduce((sum,item) => sum + totalTask(item), 0 )
  }

  return item.completedTasks
}

totalTasks(team);

answered Sep 24, 2021 at 6:17

Kuncheria

2,0401 gold badge14 silver badges18 bronze badges

Collectives™ on Stack Overflow

Finding the sum of values of objects within arrays using recursion

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related