AP CSA Unit 4 Day 14: 2D Array Diagonal Sum
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Unit 4, Data Collections • Cycle 2
Day 14 Advanced Practice • Harder Difficulty
Focus: 2D Array Diagonal Sum
Hard
2D Array Diagonal Sum
Advanced Practice Question
Format: 2D Array Diagonal Sum
What is the output?
What is the output?
int[][] matrix = {
{1, 2, 3},
{4, 5, 6},
{7, 8, 9}
};
int sum = 0;
for (int i = 0; i < matrix.length; i++) {
sum += matrix[i][i];
}
System.out.println(sum);
Difficulty: Hard |
Topic: 2D Array Diagonal Sum |
Cycle: 2 (Advanced)
Why This Answer?
Main diagonal elements: matrix[0][0]=1, matrix[1][1]=5, matrix[2][2]=9. Sum = 1+5+9 = 15.
Common Mistake
Watch Out!
Thinking diagonal means all elements, not just where row==column.
AP Exam Strategy
Main diagonal: elements where row index equals column index (i, i).
Master This Topic
This Cycle 2 HARD question tests 2d array diagonal sum. Review Unit 4 concepts to build mastery of data collections.
- Understanding 2d array diagonal sum
- Tracing code execution accurately
- Avoiding common pitfalls
Ready for More Challenges?
Cycle 2 questions prepare you for the hardest AP CSA exam questions.
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