HW1 SAMPLE ANSWERS

1.

public static String getUnique(String s1, String s2) {

        String result = "";

        for (int i = 0; i < s1.length(); i++) {
                for (int j = 0; j < s2.length(); j++) {
                        // Is the pair already in the result string?
                        if (result.indexOf("" + s1.charAt(i) + s2.charAt(j)) == -1)
                                result = result + s1.charAt(i) + s2.charAt(j) + " ");
                }
        }
        // Return result
        return result;
}

2.  The maximum length of the string is 2mn + (mn) = 3mn. 2mn comes
from the number of combinations of two characters one from each string
assuming there are no duplications. The mn term comes from the number
of spaces added: one per combination. 

3.

public static String getUnique(String s1, String s2) {

        StringBuilder result = new StringBuilder();

        for (int i = 0; i < s1.length(); i++) {
                for (int j = 0; j < s2.length(); j++) {
                        // Is the pair already in the result string?
                        if (result.indexOf("" + s1.charAt(i) + s2.charAt(j)) == -1)
                                result.append("" + s1.charAt(i) + s2.charAt(j) + " ");
                }
        }
        // Return result
        return result.toString();    // need to explicitly call toString
}

4. The StringBuilder version is expected to run faster since it does create
a new string every time we append additional characters. Concatenation
will create a new string every single time.

5.

public static void oneNamePerLine(String s1) {
        // Precondition: s1 is a string of names, comma-delimited,
        // all in uppercase
        // e.g. "TOM,MARGARET,DAVE,TIM,BARBARA,VICTOR,ANGIE,MARK,SCOTT"

        Scanner stringScan = new Scanner(s1);

        stringScan.useDelimiter(",");

        while(stringScan.hasNext()) {
                System.out.println(stringScan.next());
        }
}

6.

public static int fileSum(String s1){
        File myFile = new File(s1);
        int sum = 0;
        Scanner filescan;
        try {
                filescan = new Scanner(myFile);
        }
        catch (FileNotFoundException e) {
                return 0;        // file not found, return immediately
        }
        while(filescan.hasNextLine()) {
                sum += Integer.parseInt(filescan.nextLine());
        }
        return sum;
}

7.

public static int maxVal(int[] myArray) {
        int max = myArray[0];
        for (int i = 1; i < myArray.length; i++) {
                if (myArray[i] > max) {
                        max = myArray[i];
                }
        }
        return max;
}

8.

public static int maxValIndex(int[] myArray) {
        int maxIndex = 0;
        for (int i = 1; i < myArray.length; i++) {
                if (myArray[i] > myArray[maxIndex]) {
                        maxIndex = i;
                }
        }
        return maxIndex;
}