conqueranddivide.js

// find min and max within an array
var array = [3,4,5,12,90,23];
// function findMM(a) {
//   var min = a[0], max = min;
//   for (var i = 2, length = a.length; i < length; i ++) {
//     if (a[i] > max) {
//       max = a[i];
//     } else if (a[i] < min) {
//       min = a[i];
//     }
//   }
//   return [min, max];
// }

//  console.log(findMM(array));


function findMM (a, low, high) {
  low = low || 0;
  high = high || (a.length - 1);
  var max = a[0];
  var min = a[1];

  if (high - low <= 0) {
    return [min, max];
  } else if (high - low === 1) {
    // comparision 

    if (a[high] > a[low]) {
      min = a[low];
      max = a[high];
    } else {
      min = a[high];
      max = a[low];
    }
    return [min, max];
  } else {
    var mid = Math.floor((low + high) / 2);
    var mm1 = findMM(a, low, mid);
    var mm2 = findMM(a, mid + 1, high);
    var min1 = mm1[0];
    var max1 = mm1[1];
    var min2 = mm2[0];
    var max2 = mm2[1];
    // comparisions 
    if (min1 < min2) {
      min = min1;
    } else {
      min = min2;
    }

    if (max1 > max2) {
      max = max1;
    } else {
      max = max2;
    }
    return [min, max];
  }
}
console.log(findMM(array));