188 (1)

stevencooks · stevencooks · commit d38e8d205a5e · 2015-10-01T23:32:01.000-04:00
diff --git a/src/_188_BestTimeToBuyAndSellStockIV/Solution.java b/src/_188_BestTimeToBuyAndSellStockIV/Solution.java
@@ -0,0 +1,38 @@
+/**
+ * Time : O() ; Space: O()
+ * @tag : Dynamic Programming
+ * @by  : Steven Cooks
+ * @date: Sep 30, 2015
+ ***************************************************************************
+ * Description:
+ * 
+ * Say you have an array for which the ith element is the price of a given stock on day i. 
+ * 
+ * Design an algorithm to find the maximum profit. You may complete at most k transactions. 
+ * 
+ * Note: You may not engage in multiple transactions at the same time 
+ * (ie, you must sell the stock before you buy again).
+ * 
+ ***************************************************************************
+ * {@link https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iv/ }
+ * @reference {@link https://leetcode.com/discuss/15153/a-clean-dp-solution-which-generalizes-to-k-transactions }
+ */
+package _188_BestTimeToBuyAndSellStockIV;
+
+/** see test {@link _188_BestTimeToBuyAndSellStockIV.SolutionTest } */
+public class Solution {
+    
+    public int maxProfit(int k, int[] prices) {
+        int n = prices.length;
+        int[][] f = new int[k + 1][n];
+        for (int i = 0; i < k; i++) {
+            int tmpMax = f[k - 1][0] - prices[0];
+            for (int j = 1; j < n; j++) {
+                f[i][j] = Math.max(f[i][j - 1], prices[j] + tmpMax);
+                tmpMax = Math.max(tmpMax, f[i - 1][j] - prices[j]);
+            }
+        }
+        return k;
+    }
+
+}
