Create 188. Best Time to Buy and Sell Stock IV-dp-hard.md

Author: tmp-coder

leetcode/188. Best Time to Buy and Sell Stock IV-dp-hard.md

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+```cpp
+class Solution {
+public:
+    int maxProfit(int k,const vector<int>& prices) {
+        if(k<1 || prices.size() <=1)
+            return 0;
+        if(k > prices.size() / 2){
+            int ans = 0;
+            for(int i=1;i<prices.size() ; ++i)
+                ans += max(0,prices[i] - prices[i-1]);
+            return ans;
+        }
+
+        vector<int> sell(k+1,0);
+        vector<int> buy(k+1,INT32_MIN>>2);
+        for(int price : prices){
+            for(int i=1; i<=k ; ++i){
+                buy[i] = max(buy[i], sell[i-1] - price);
+                sell[i] = max(sell[i], buy[i] + price);
+            }
+        }
+        return sell[k];
+    }
+};
+```