Peaks and Valleys

1. Sort the array into an alternating sequence of peaks and valleys
• Compare closed 3 items and swap them necessarily
  

  for (int i = 1; i < array.length; i+= 2) {
   int biggestIndex = maxIndex(array, i-1, i, i+1); 
   if (i != biggestIndex) {
     swap(array, i, biggestIndex); 
   } 
  }

2. TODO