Create buy_sell_with_cooldown_dp.cpp

Author: avidLearnerInProgress

buy_sell_with_cooldown_dp.cpp

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+//fsm based solution
+
+class Solution {
+private:
+    const int STATE_NUM = 3, STEP_NUM = 2, S_BUY = 0, S_SELL = 1, S_COOL = 2;
+public:
+    int maxProfit(vector<int>& prices) {
+        int state[STATE_NUM][STEP_NUM], i, j, steps = prices.size(),cur = 0, next = 1;
+        
+        fill_n(&state[0][0], STATE_NUM*STEP_NUM, INT_MIN);
+        
+        for(i=0,state[0][0]=0;i<steps;++i, swap(cur, next)) {
+            state[S_BUY][next]  = max(state[S_BUY][cur], state[S_COOL][cur]);
+            state[S_SELL][next] = max(state[S_BUY][cur]-prices[i], state[S_SELL][cur]);
+            state[S_COOL][next] = state[S_SELL][cur] + prices[i];
+        }
+        return max(state[S_BUY][cur], state[S_COOL][cur]);
+    }
+};