MinCostTickets.java

package com.learning.leet.problems;

import java.util.HashSet;
import java.util.Set;

/**
 * Created by sargonbenjamin on 7/9/19.
 * https://leetcode.com/problems/minimum-cost-for-tickets/
 */
public class MinCostForTickets {

    public int mincostTickets(int[] days, int[] costs) {


        int[] minCost = new int[366];
        Set<Integer> setRideDays = new HashSet<>();

        for(int day : days){
            setRideDays.add(day);
        }

        for(int i = 1; i<minCost.length; i++){
            if(setRideDays.contains(i)){
                int dayMinCost = minCost[Math.max(0,i-1)]+costs[0];
                int weekMinCost = minCost[Math.max(0,i-7)]+costs[1];

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

                int monthCost = minCost[Math.max(0,i-30)]+costs[2];
                minCost[i]=Math.min(min,monthCost);
            }else {
                minCost[i]=minCost[i-1];
            }
        }

        return minCost[365];

    }
}