MinCostTicketsRecursive.java

public int mincostTickets(int[] days, int[] costs) {
      Set<Integer> setRideDays = new HashSet<>();

        for(int day : days){
            setRideDays.add(day);
        }
        
        int[] minCostCache = new int[366];
        for(int i = 0; i<minCostCache.length;i++){
            minCostCache[i]=-1;
        }
        
        minCostCache[0]=0;
        return mincostTicketsHelper(costs,minCostCache, setRideDays, days[days.length-1]);

        
    }
    
        public int mincostTicketsHelper(int[] costs, int[] minCostCache, Set<Integer> setRideDays, int currDay){

        if(currDay<=0)return minCostCache[0];
            
        if(minCostCache[currDay]>=0)return minCostCache[currDay];

        if(setRideDays.contains(currDay)){
            int dayMinCost = mincostTicketsHelper(costs,minCostCache,setRideDays,currDay-1) + costs[0];
            int weekMinCost = mincostTicketsHelper(costs,minCostCache,setRideDays,currDay-7)+costs[1];

            int min = Math.min(dayMinCost,weekMinCost);

            int monthCost = mincostTicketsHelper(costs,minCostCache,setRideDays,currDay-30)+costs[2];
            minCostCache[currDay]=Math.min(min,monthCost);
        }else {
            minCostCache[currDay]=mincostTicketsHelper(costs,minCostCache,setRideDays,currDay-1);
        }


        return minCostCache[currDay];

    }