buildProduct.java

private static String buildProducts(String parts) {
        int acumA = 0;
        int acumB = 0;
        int acumC = 0;
        int acumD = 0;
        int acumE = 0;
        
        for (int i = 0;  i < parts.length(); i++) {
             switch (parts.charAt(i)) {
                 case 'a' : ++acumA;
                    break;
                 case 'b' : ++acumB;
                     break;
                 case 'c' : ++acumC;
                     break;
                 case 'd' : ++acumD;
                     break;
                 case 'e' : ++acumE;
                     break;
             }
        }
        
        return "{\"Shelf\" :" +  acumA + ", \"Stool\" : "  + countProductComplete(acumB, acumC, 3) + ", \"Table\" : " +  countProductComplete(acumD, acumE, 4) + "}";
    }

    private static int countProductComplete(int partA, int partB, int minPiecesPartB) {
        if (partA >= 1 && partB >= minPiecesPartB ) {
            int maxPiecesPartB = partA * minPiecesPartB;
            return (partB >= maxPiecesPartB ) ? partA : partB / minPiecesPartB;
        }
        return 0;
    }