Best Time to Buy and Sell Stock V

3573.Best Time to Buy and Sell Stock V.cpp

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+class Solution {
+public:
+    vector<int> prices;
+    long long mn = -1e14;
+    vector<vector<vector<long long>>> dp;
+    long long f(int i, int k, int state){
+        if(i == prices.size()){
+            return state == 0 ? 0 : mn;
+        }
+        if(dp[i][k][state] != mn) return dp[i][k][state];
+
+        long long p = prices[i];
+        long long profit = mn;
+        profit = max(profit, f(i + 1, k, state));
+
+        if(state == 0){
+            profit = max(profit, f(i+1, k, 1) - p);
+            profit = max(profit, f(i+1, k, 2) + p);
+        }
+        else if(k > 0){ // have transactions left
+            if(state == 1){
+                profit = max(profit, f(i+1, k-1, 0) + p);
+
+            }
+            else{
+                 profit = max(profit, f(i+1, k-1, 0) - p);
+            }
+        }
+        return dp[i][k][state] = profit;
+    }
+
+    long long maximumProfit(vector<int>& prices, int k) {
+        this->prices = prices;
+        dp.assign(prices.size() + 1, vector<vector<long long>> (k + 1, vector<long long> (3, mn)));
+        return f(0, k, 0);  
+    }
+};