谁的钱最多 - Codewars 挑战 - JavaScript

Question

Link to challenge

You're going on a trip with some students and it's up to you to keep track of how much money each Student has. A student is defined like this:

class Student {
  constructor(name, fives, tens, twenties) {
    this.name = name;
    this.fives = fives;
    this.tens = tens;
    this.twenties = twenties;
  }
}

As you can tell, each Student has some fives, tens, and twenties. Your job is to return the name of the student with the most money. If every student has the same amount, then return "all".

Notes:

Each student will have a unique name

There will always be a clear winner: either one person has the most, or everyone has the same amount

If there is only one student, then that student has the most money

---

I've tried this:

 function mostMoney(students) { //get array of totals let array = []; students.forEach((value, index) => { let total = ((5 * value.fives) + (10 * value.tens) + (20 * value.twenties)); array.push([total, value.name]); }); //sort array of totals array = array.sort((a, b) => b[0] - a[0]); console.log('array****', array); //check if all totals are equal - if they are, return 'all' if (array.every((el, i, array) => (el)[0]) === array[0][0]) { return 'all'; } else { return array[0][1]; } }

What doesn't make sense to me is that when I console.log('array****', array); in codewars it looks like:

array**** [ [ 50, 'Eric' ],
  [ 40, 'Andy' ],
  [ 40, 'Stephen' ],
  [ 40, 'Phil' ],
  [ 30, 'David' ] ]
array**** [ [ 50, 'Eric' ],
  [ 40, 'Andy' ],
  [ 40, 'Stephen' ],
  [ 40, 'Phil' ],
  [ 30, 'Cameron' ],
  [ 30, 'Geoff' ],
  [ 30, 'David' ] ]
array**** [ [ 40, 'Andy' ] ]
array**** [ [ 40, 'Stephen' ] ]
array**** [ [ 30, 'Cameron' ], [ 30, 'Geoff' ] ]

Why does it look like that? I would think that after sorting, my console.log('array***', array) should just look like:

array**** [ [ 50, 'Eric' ],
  [ 40, 'Andy' ],
  [ 40, 'Stephen' ],
  [ 40, 'Phil' ],
  [ 30, 'Cameron' ],
  [ 30, 'Geoff' ],
  [ 30, 'David' ] ]

When I initially console.log(students) , it looks like an array:

[ Student { name: 'Andy', fives: 0, tens: 0, twenties: 2 },
  Student { name: 'Stephen', fives: 0, tens: 4, twenties: 0 },
  Student { name: 'Eric', fives: 8, tens: 1, twenties: 0 },
  Student { name: 'David', fives: 2, tens: 0, twenties: 1 },
  Student { name: 'Phil', fives: 0, tens: 2, twenties: 1 } ]

So I'm trying to collect all of the totals in an array with my forEach loop, and then sorting that array after looping - what's wrong with that logic?

Answer 1

Working solution: )

function mostMoney(students) {
  let array = [];
  if (students.length === 1) {
     return students[0].name;
  }
  students.forEach((value, index) => {
     let total = ((5 * value.fives) + (10 * value.tens) + (20 * value.twenties));
     array.push([total, value.name]);
  });
  array = array.sort((a, b) => b[0] - a[0]);
  if (array.every((el, i, array) => el[0] === array[0][0])) {
    return 'all'; 
  }
  else {
    return array[0][1];
  }
}

There was in fact a problem with my .every - I was doing (el)[0]) instead of el[0] , and then I also wasn't properly checking for when there was only one student passed into mostMoney .

Thanks all for shedding light on the console.log issue. Codewars was console.logging multiple times because, as you all mentioned, it's running multiple tests.

Answer 2

I can suggest as solution:

  function mostMoney(students) {
     //deep copy of argument
     let input = [...students];
     // sort students by total descending
     let sum = st => st.fives * 5 + st.tens * 10 + st.twenties * 20;
     let comparator = (st1,st2) => sum(st2) - sum(st1);
     input.sort(comparator);     
     // result
     //just compare the first two students
     if(input.length >=2 && sum(input[0]) == sum(input[1])){
      return 'all';
     }
     else{
      return input[0].name;
     }
  }