Shoddy script for finding max rectangular area under a curve, for histograms in this case.

index.js

function maxArea (original, histogram, maxArray) {
  if (!histogram) {
    histogram = original.slice(0);
  }
  maxArray = maxArray || new Array(histogram.length);

  var currVal = histogram.pop();

  if (currVal===0 || !histogram.length) {
    maxArray[histogram.length] = currVal;
  }
  else {
    var localMaxes=[],max = 1;
    for (var j = currVal; j>0; j--) {
      for (var i = histogram.length-1; i >= 0; i--) {
        var itrVal = histogram[i];

        if (itrVal < currVal) {
          localMaxes[j] = max * currVal;
          break;
        }
        else {
          max++;
          localMaxes[j] = max * currVal;
        }
      }
    }
  }
  
  if (!histogram.length) {
    return _.max(maxArray);
  }
  else {
    return maxArea(original, histogram, maxArray);
  }  
}

// #
// # #       #
// # # #   # # # #
// # # #   # # # # #
// 4,3,2,0,2,3,2,2,1
console.log(maxArea([4,3,2,0,2,3,2,2,1]))
//> 8

// #
// # #       #   #
// # # #   # # # #
// # # #   # # # # #
// 4,3,2,0,2,3,2,3,1
console.log(maxArea([4,3,2,0,2,3,2,3,1]))
//> 8