Merge pull request #2020 from lynndove/master

增加了0188.买卖股票的最佳时机IV的解法二

problems/0188.买卖股票的最佳时机IV.md

@@ -328,6 +328,42 @@ func max(a, b int) int {
 }
 ```
 
+版本二: 三维 dp数组
+```go
+func maxProfit(k int, prices []int) int {
+	length := len(prices)
+	if length == 0 {
+		return 0
+	}
+	// [天数][交易次数][是否持有股票]
+	// 1表示不持有/卖出, 0表示持有/买入
+	dp := make([][][]int, length)
+	for i := 0; i < length; i++ {
+		dp[i] = make([][]int, k+1)
+		for j := 0; j <= k; j++ {
+			dp[i][j] = make([]int, 2)
+		}
+	}
+	for j := 0; j <= k; j++ {
+		dp[0][j][0] = -prices[0]
+	}
+	for i := 1; i < length; i++ {
+		for j := 1; j <= k; j++ {
+			dp[i][j][0] = max188(dp[i-1][j][0], dp[i-1][j-1][1]-prices[i])
+			dp[i][j][1] = max188(dp[i-1][j][1], dp[i-1][j][0]+prices[i])
+		}
+	}
+	return dp[length-1][k][1]
+}
+
+func max188(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
+```
+
 Javascript:
 
 ```javascript