From bd3d65c41530e2f8268986ce9f4b13d889d5925d Mon Sep 17 00:00:00 2001
From: DoubleYellowIce <65336599+DoubleYellowIce@users.noreply.github.com>
Date: Thu, 19 Aug 2021 14:34:15 +0800
Subject: [PATCH] =?UTF-8?q?Update=200188.=E4=B9=B0=E5=8D=96=E8=82=A1?=
 =?UTF-8?q?=E7=A5=A8=E7=9A=84=E6=9C=80=E4=BD=B3=E6=97=B6=E6=9C=BAIV.md?=
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---
 .../0188.买卖股票的最佳时机IV.md     | 21 ++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/problems/0188.买卖股票的最佳时机IV.md b/problems/0188.买卖股票的最佳时机IV.md
index 9fe7a919..66676a7a 100644
--- a/problems/0188.买卖股票的最佳时机IV.md
+++ b/problems/0188.买卖股票的最佳时机IV.md
@@ -196,7 +196,7 @@ class Solution {
     }
 }
 
-// 版本二: 空间优化
+// 版本二: 二维 dp数组
 class Solution {
     public int maxProfit(int k, int[] prices) {
         if (prices.length == 0) return 0;
@@ -220,6 +220,25 @@ class Solution {
         return dp[len - 1][k*2];
     }
 }
+
+//版本三：一维 dp数组
+class Solution {
+    public int maxProfit(int k, int[] prices) {
+        //在版本二的基础上，由于我们只关心前一天的股票买入情况，所以只存储前一天的股票买入情况
+        if(prices.length==0)return 0;
+        int[] dp=new int[2*k+1];
+        for (int i = 1; i <2*k ; i+=2) {
+            dp[i]=-prices[0];
+        }
+        for (int i = 0; i <prices.length ; i++) {
+            for (int j = 1; j <2*k ; j+=2) {
+                dp[j]=Math.max(dp[j],dp[j-1]-prices[i]);
+                dp[j+1]=Math.max(dp[j+1],dp[j]+prices[i]);
+            }
+        }
+        return dp[2*k];
+    }
+}
 ```