Merge pull request youngyangyang04#2788 from markwang1992/123-maxProfit

123.买卖股票的最佳时机III增加Go版本二和版本三

problems/0123.买卖股票的最佳时机III.md

@@ -317,6 +317,7 @@ class Solution:
 ### Go:
 
 ```go
+// 版本一
 func maxProfit(prices []int) int {
     dp := make([][]int, len(prices))
     for i := 0; i < len(prices); i++ {
@@ -344,6 +345,58 @@ func max(a, b int) int {
 }
 ```
 
+```go
+// 版本二
+func maxProfit(prices []int) int {
+    if len(prices) == 0 {
+        return 0
+    }
+    dp := make([]int, 5)
+    dp[1] = -prices[0]
+    dp[3] = -prices[0]
+    for i := 1; i < len(prices); i++ {
+        dp[1] = max(dp[1], dp[0] - prices[i])
+        dp[2] = max(dp[2], dp[1] + prices[i])
+        dp[3] = max(dp[3], dp[2] - prices[i])
+        dp[4] = max(dp[4], dp[3] + prices[i])
+    }
+    return dp[4]
+}
+
+func max(x, y int) int {
+    if x > y {
+        return x
+    }
+    return y
+}
+```
+
+```go
+// 版本三
+func maxProfit(prices []int) int {
+    if len(prices) == 0 {
+        return 0
+    }
+    dp := make([][5]int, len(prices))
+    dp[0][1] = -prices[0]
+    dp[0][3] = -prices[0]
+    for i := 1; i < len(prices); i++ {
+        dp[i][1] = max(dp[i-1][1], 0 - prices[i])
+        dp[i][2] = max(dp[i-1][2], dp[i-1][1] + prices[i])
+        dp[i][3] = max(dp[i-1][3], dp[i-1][2] - prices[i])
+        dp[i][4] = max(dp[i-1][4], dp[i-1][3] + prices[i])
+    }
+    return dp[len(prices)-1][4]
+}
+
+func max(x, y int) int {
+    if x > y {
+        return x
+    }
+    return y
+}
+```
+
 ### JavaScript:
 
 > 版本一：