review300: best time to buy and sell stock4

bestTimeToBuyAndSellStock4/review300.go

@@ -0,0 +1,27 @@
+package main
+
+import "math"
+
+func maxProfit(k int, prices []int) int {
+	dpHold := make([]int, len(prices)+1)
+	dpProfit := make([]int, len(prices)+1)
+	dpHold[0] = math.MinInt32
+	dpProfit[0] = 0
+	max := func(a, b int) int {
+		if a > b {
+			return a
+		}
+		return b
+	}
+	for k > 0 {
+		for i := range prices {
+			// dpProfit[i+1], 只能使用k-1轮的盈利
+			// 不能使用dpProfit[i], 前面交易盈利, 单次交易
+			dpHold[i+1] = max(dpHold[i], dpProfit[i+1]-prices[i])
+			dpProfit[i+1] = max(dpProfit[i], prices[i]+dpHold[i])
+		}
+
+		k--
+	}
+	return dpProfit[len(prices)]
+}