Create stock-price.py

Author: learning-zone

stock-price.py

@@ -0,0 +1,97 @@
+def get_max_profit(prices):
+    """ Finds the maximum profit for buying and selling stock within a day.
+
+    >>> stock_prices_yesterday = [10, 7, 5, 8, 11, 9]
+    >>> get_max_profit(stock_prices_yesterday)
+    6
+
+    >>> stock_prices_yesterday = [10, 3]
+    >>> get_max_profit(stock_prices_yesterday)
+    -7
+
+    >>> stock_prices_yesterday = [1, 10, 7, 14, 2, 11]
+    >>> get_max_profit(stock_prices_yesterday)
+    13
+
+    >>> stock_prices_yesterday = [11, 10, 9, 8, 2, 1]
+    >>> get_max_profit(stock_prices_yesterday)
+    -1
+
+    >>> stock_prices_yesterday = [11, 9, 5, 2, 2, 0]
+    >>> get_max_profit(stock_prices_yesterday)
+    0
+
+    >>> stock_prices_yesterday = [1, 1, 1, 1, 1, 1]
+    >>> get_max_profit(stock_prices_yesterday)
+    0
+    """
+
+    # Runtime: O(n^2)
+    # Spacetime: O(n)
+
+
+    max_profit = prices[1] - prices[0]
+
+    for a in range(len(prices)):  # O(n)
+        for b in range(a + 1, len(prices)):  # O(n)
+            gain_loss = prices[b] - prices[a]
+            if gain_loss > max_profit:
+              max_profit = gain_loss
+    print max_profit
+
+
+def get_max_profit_optimized(prices):
+    """ Finds the maximum profit for buying and selling stock within a day.
+
+    >>> stock_prices_yesterday = [10, 7, 5, 8, 11, 9]
+    >>> get_max_profit_optimized(stock_prices_yesterday)
+    6
+
+    >>> stock_prices_yesterday = [10, 3]
+    >>> get_max_profit_optimized(stock_prices_yesterday)
+    -7
+
+    >>> stock_prices_yesterday = [1, 10, 7, 14, 2, 11]
+    >>> get_max_profit_optimized(stock_prices_yesterday)
+    13
+
+    >>> stock_prices_yesterday = [11, 10, 9, 8, 2, 1]
+    >>> get_max_profit_optimized(stock_prices_yesterday)
+    -1
+
+    >>> stock_prices_yesterday = [11, 9, 5, 2, 2, 0]
+    >>> get_max_profit_optimized(stock_prices_yesterday)
+    0
+
+    >>> stock_prices_yesterday = [1, 1, 1, 1, 1, 1]
+    >>> get_max_profit_optimized(stock_prices_yesterday)
+    0
+    """
+
+
+    # Runtime: O(n)
+    # Spacetime: O(1)
+
+
+    max_profit = prices[1] - prices[0]
+    low = prices[0]
+
+    for i in prices:
+
+        # Skip the first price in list
+        if prices[0] == i:
+            continue
+
+        potential_profit = i - low
+        max_profit= max(max_profit, potential_profit)
+        low = min(low, i)
+
+    print max_profit
+
+
+if __name__ == '__main__':
+    import doctest
+    results = doctest.testmod()
+
+    if results.failed == 0:
+        print "ALL TESTS PASSED"