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Problem #1:
2 points each, 1 point for correct value of wrong type (missing parens, no .0)
Problem #2:
1 point for each of the 12 values
-1 if any error in surrounding text (dittos not allowed)
-4 if two columns transposed
-8 if you need to transpose twice
Problem #3:
each is 3 points, -1 for a single number wrong or for a single transpose
-2 if columns transposed
-2 if formatting error (e.g., commas between numbers)
-1 if reversed
-0 if output is quoted
-0 if underscore for space
Problem #4:
column 1 is 1 point, column 2 is 2 points
-2 if columns transposed
-2 if formatting error (e.g., commas between numbers)
-0 if output is quoted
-0 if underscore for space
Problem #5:
1 point per blank
Problem #6
Solutions:
public static boolean hasOddEven(int x, int y, int z) {
return x % 2 != y % 2 || y % 2 != z % 2;
}
public static boolean hasOddEven(int x, int y, int z) {
if (x % 2 == 0 && y % 2 == 0 && z % 2 == 0) {
return false;
} else if (x % 2 == 1 && y % 2 == 1 && z % 2 == 1) {
return false;
} else {
return true;
}
}
3 correct header (-1 per error)
1 return something somewhere
3 three mods (x % 2, y % 2, z % 2) in a meaningful context like an if, a sum, a
comparison, a boolan expression with && or || (1 point for each)
8 cases
eee case <- 2 points
ooo case <- 2 points
eeo case
eoe case
eoo case
oeo case
ooe case
oee case
2 determines false when all even based on complete tests
2 determines false when all odd based on complete tests
2 determines true in at least 2 of the mixed cases based on tests
2 determines true in all 6 of the mixed cases based on tests
special cases
-2 if they return the negation of the right answer
-4 if we can make a single transformation to their code that gets them a higher
score (e.g., adding parentheses)
Problem #7
Solution:
public static void findRange(Scanner console) {
System.out.print("number (0 to quit)? ");
int number = console.nextInt();
int max = number;
int min = number;
while (number != 0) {
if (number > max) {
max = number;
} else if (number < min) {
min = number;
}
System.out.print("number (0 to quit)? ");
number = console.nextInt();
}
int range = max - min;
System.out.println("range = " + range);
}
1 correct header (non-void return okay if they return something of that type)
2 loop while number != 0
1 attempt
1 correct
3 prompt and read number inside loop
2 attempt -- prompt and console.nextInt() somewhere
1 correct -- print, correctly prompts and stores (doesn't read twice)
1 idea: some attempt at max/min computation
2 max computation
1 max declared/initialized properly outside loop
1 max updated correctly in loop
2 min computation
1 min declared/initialized properly outside loop
1 min updated correctly in loop
2 handles terminating 0 correctly
2 correctly print what they think is the range after loop (no double jeopardy
if they didn't use a max/min approach)
1 attempt
1 correct
Problem #8
Solutions:
public static String undouble(String s) {
String result = "";
if (s.length() > 0) {
char last = s.charAt(0);
result += last;
for (int i = 1; i < s.length(); i++) {
if (s.charAt(i) != last) {
result += s.charAt(i);
}
last = s.charAt(i);
}
}
return result;
}
public static String undouble2(String s) {
String result = "";
if (s.length() > 0) {
result = s.substring(0, 1);
for (int i = 1; i < s.length(); i++) {
if (s.charAt(i) != s.charAt(i - 1)) {
result += s.charAt(i);
}
}
}
return result;
}
Can get up to 3 points for any of the following good things:
1 correct header
1 for loop involving s.length
1 returning a String
1 s.charAt(i) or s.substring(i, i + 1)
1 str += charAt or substring
1 comparing charAt(i) with charAt(i + 1) (or substring)
If both of the last two (concat & adjacent comparison), then give to Stuart to
grade for score of 4-9.
-1 if fails on empty string or case like ccaatt
-2 if their code doesn't handle 1st/last char properly
-0 String result = s.charAt(0);
-0 for String new = ... (reserved word)
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Stuart Reges
Last modified: Fri Sep 16 15:55:25 PDT 2011