balance

balance.js

var userSums = [{name: 'ayal', sum: 400}, {name: 'tomer', sum: 300}, {name: 'guy', sum: 250}, {name: 'ronni', sum: 0}, {name: 'max', sum: 0}];
var sum = userSums.reduce((acc,u)=>acc+u.sum,0);
var usum = sum / userSums.length;


userSums.map(x=>(x.balance = x.sum - usum) && (x.gotgave = 0));

var balanceUsers = (u1,u2)=> {
   if (u1.balance < 0 && u2.balance > 0) {
     // u1 pays u2
     let topay = 0;
     //debugger;
     if (Math.abs(u1.balance) >= u2.balance) { 
       topay = u2.balance;
     }
     else {
       topay = -u1.balance;
     }
     console.log(u1.name, 'pays', u2.name, topay);
     u1.balance += topay;
     u1.gotgave -= topay;
     u2.balance -= topay;
     u2.gotgave += topay;
   }
   if (u2.balance < 0 && u1.balance > 0) {
     balanceUsers(u2, u1);
   }
};

var balanceUser = (u) => {
  for (let userSum of userSums) {
          balanceUsers(u, userSum)
  }
}

console.log('every one should pay', usum);


for (let userSum of userSums) {
  balanceUser(userSum);
}

console.log(userSums);