Optimise Exact

gistfile1.java

import java.util.Arrays;


public class Main {

	public static int startStock = 20;
	public static int deliveryTime = 2;
	public static int box = 30;
	
	public static void main(String[] args) {
		// TODO Auto-generated method stub

		int[] buyings = new int[14];
		int[] sales = new int[] { 0, 0, 10, 20, 30, 10, 20, 30, 45, 25, 5, 45, 45, 20 };
		
		// Optimal
		int[] bestBuyings = new int[14];
		int bestCosts = Integer.MAX_VALUE;
		
		int max = 2;
		int iterations = (int) Math.pow(max+1, buyings.length);
		System.out.println("Iterations: "+iterations);
		//int show = 1000000;
		while(iterations-- > 0){
			int c = costs(startStock, buyings, sales);
			//System.out.println("Eval: "+Arrays.toString(buyings) + "; costs = "+c);
			if(c < bestCosts){
				bestCosts = c;
				bestBuyings = buyings.clone();
				System.out.println("New best "+c+"! Go girl! "+Arrays.toString(bestBuyings));
			}
			next(buyings, max);
		}
		
		System.out.println("Buyings: "+Arrays.toString(bestBuyings));
		System.out.println("Costs: "+bestCosts);
	}
	
	public static int[] next(int[] list, int max){
		int curry = 1;
		for(int i = 0; i < list.length; i++){
			if(curry + list[i] > max){
				list[i] = 0;
				curry = 1;
			} else {
				list[i] += curry;
				curry = 0;
			}
		}
		return list;
	}

	public static int costs(int startStock, int[] buyPerMonth, int[] sales){
		int totalCost = 0;
		int[] stockAtTime = new int[buyPerMonth.length];
		
		for(int m = 0; m < buyPerMonth.length; m++){
			stockAtTime[m] = m == 0 ? startStock : stockAtTime[m-1];
			// Deliveries
			stockAtTime[m] += m >= deliveryTime ? buyPerMonth[m - deliveryTime]*box : 0;
			// Penalty
			int toLess = Math.max(0, sales[m] - stockAtTime[m]); 
			stockAtTime[m] -= Math.min(sales[m], stockAtTime[m]);
			totalCost += toLess * 2000;
			// Warehouse			
			totalCost += stockAtTime[m] * 400;
			
		}
		
		return totalCost;
		
	}
	
}

Boxes: [0, 1, 1, 0, 1, 1, 1, 1, 0, 2, 1, 1, 0, 0]
Costs: 80000