AMD Interview Question for Developer Program Engineers

Country: India

Comment hidden because of low score. Click to expand.
of 0 vote

Assuming that

- Ai-1 = 1 when i <0
- Ai+1 = 1 when i > A.length
- The array is unsorted and should not be sorted

One solution is to scan the entire array for the maximum coins, then pop that balloon until no balloons remain.

function maxCoins(arr) {
  var coins = 0;
  while(array.length > 0) {
   // find balloon that would yield most coins
   var i = findBalloonIndexWithHighestYield(arr); // This function name would probably be abbreviated on a whiteboard 
     coins += calculateYield(arr, i);
     arr.splice(i, 1); // Pop balloon

  return coins;

function findBalloonIndexWithHighestYield(arr) {
   var maxIndex = 0;
   for(var i = 1; i < arr.length; i++) {
     if(calculateYield(arr, i-1) > calculate(arr, i)) {
       maxIndex = i;

   return maxIndex;

function calculateYield(arr, index) {
   var left = 1;  
   var right = 1;
   if (index > 0) { 
      left = arr[index-1];

   if (index < arr.length-1) {
     right = arr[index+1];
   return left * right;

This algorithm would run in O(n^2) since every element is scanned n times in the worst case.

- Anonymous May 15, 2016 | Flag Reply
Comment hidden because of low score. Click to expand.
of 0 vote

Information insufficient. If i-1 and i+1 become adjacent, how do we get the answer 20.

- sanjogj43 November 20, 2016 | Flag Reply

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