best time to buy and sell stock

Author: jackzhenguo

Array/array.Console/Array.Lib/BestTimetoBuyandSellStock.cs

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+/* ==============================================================================
+ * 功能描述：ThirdMaximumNumber  
+ * 创 建 者：gz
+ * 创建日期：2017/5/1 8:25:57
+ * ==============================================================================*/
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+// Say you have an array for which the ith element is the price of a given stock on day i.
+
+// If you were only permitted to complete at most one transaction (ie, buy one and sell one share of the stock), design an algorithm to find the maximum profit.
+
+// Example 1:
+// Input: [7, 1, 5, 3, 6, 4]
+// Output: 5
+
+// max. difference = 6-1 = 5 (not 7-1 = 6, as selling price needs to be larger than buying price)
+// Example 2:
+// Input: [7, 6, 4, 3, 1]
+// Output: 0
+
+// In this case, no transaction is done, i.e. max profit = 0.
+namespace Array.Lib
+{
+    /// <summary>
+    /// 121. Best Time to Buy and Sell Stock
+    /// </summary>
+    public class BuyAndSellSln
+    {
+        public int MaxProfit(int[] prices) 
+	   {
+        int premax = 0;
+        int curmax = 0;
+        for(int i=1; i<prices.Length; i++)
+        {
+            int cal = prices[i]-prices[i-1];
+            curmax = Math.Max(cal,cal+curmax);
+            premax = Math.Max(curmax,premax);
+        }
+        return premax;
+	   }
+
+    }
+}