Jimmy-gay

var ERT_YesterdayStockPrice = [10, 7, 4, 8, 12, 9, 200, 2, 100];

function calc_max_profit(ERT_YesterdayStockPrice) {
    var result = {
        "buyAt" : 0,
        "sellAt" : 0,
        "profit" : 0
    }
    right = 0;
    left = 0;
    for (var i = 0; i < ERT_YesterdayStockPrice.length; i++){
        if (ERT_YesterdayStockPrice[i] < ERT_YesterdayStockPrice[left]) {
            left = i;
            if (left > right) {
                right = left;
            }
        }
        if (ERT_YesterdayStockPrice[i] >= ERT_YesterdayStockPrice[right]) {
            right = i;
        }
        if (ERT_YesterdayStockPrice[right] - ERT_YesterdayStockPrice[left] > result.profit) {
            result.profit = ERT_YesterdayStockPrice[right] - ERT_YesterdayStockPrice[left];
            result.sellAt = right;
            result.buyAt = left;
        }
    }
    return result;
}