Chapter 9 Beginner 52 Questions

Practice Questions — Loop Control and Pattern Printing

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8 Easy

12 Medium

9 Hard

Topic-Specific Questions

Question 1

Easy

What is the output?

for (int i = 1; i <= 5; i++) {
    if (i == 3) break;
    System.out.print(i + " ");
}

break exits the loop when i is 3.

1 2

Question 2

Easy

What is the output?

for (int i = 1; i <= 5; i++) {
    if (i == 3) continue;
    System.out.print(i + " ");
}

continue skips the current iteration.

1 2 4 5

Question 3

Easy

What is the output?

for (int i = 10; i >= 1; i--) {
    if (i % 2 != 0) continue;
    System.out.print(i + " ");
}

Odd numbers are skipped by continue.

10 8 6 4 2

Question 4

Easy

How many stars are printed?

for (int i = 1; i <= 4; i++) {
    for (int j = 1; j <= i; j++) {
        System.out.print("*");
    }
    System.out.println();
}

Row 1: 1 star, Row 2: 2, Row 3: 3, Row 4: 4.

10 stars total (1+2+3+4)

Question 5

Medium

What is the output?

outer:
for (int i = 1; i <= 3; i++) {
    for (int j = 1; j <= 3; j++) {
        if (j == 2) continue outer;
        System.out.print(i + "" + j + " ");
    }
}

continue outer skips to the next iteration of the outer loop.

11 21 31

Question 6

Medium

What is the output?

outer:
for (int i = 0; i < 3; i++) {
    for (int j = 0; j < 3; j++) {
        if (i == 1 && j == 1) break outer;
        System.out.print(i + "" + j + " ");
    }
}

break outer exits both loops at i=1, j=1.

00 01 02 10

Question 7

Medium

What is the output?

int n = 4;
for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n - i; j++) {
        System.out.print(" ");
    }
    for (int j = 1; j <= i; j++) {
        System.out.print(i + " ");
    }
    System.out.println();
}

Each row prints (n-i) spaces then i copies of the row number.

Question 8

Medium

What is the output?

int num = 1;
for (int i = 1; i <= 3; i++) {
    for (int j = 1; j <= i; j++) {
        System.out.print(num++ + " ");
    }
    System.out.println();
}

This is Floyd's triangle. num increments continuously.

1
2 3
4 5 6

Question 9

Hard

What is the output?

for (int i = 1; i <= 4; i++) {
    for (int j = 1; j <= 4; j++) {
        if (i + j == 5) {
            System.out.print("* ");
        } else {
            System.out.print("  ");
        }
    }
    System.out.println();
}

Print * only where i + j equals 5. Otherwise print spaces.

Question 10

Hard

What is the output?

int n = 4;
for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n; j++) {
        if (i == 1 || i == n || j == 1 || j == n) {
            System.out.print("* ");
        } else {
            System.out.print("  ");
        }
    }
    System.out.println();
}

Stars print on the borders (first/last row, first/last column).

* * * * 
*     * 
*     * 
* * * *

Question 11

Medium

What is the difference between break and continue? When would you use each?

Think about whether you want to stop completely or skip one iteration.

break terminates the entire loop immediately. continue skips only the current iteration and proceeds to the next. Use break when a search is complete or an error requires stopping. Use continue when certain iterations should be skipped (e.g., skipping invalid inputs) while the loop continues processing others.

Question 12

Hard

Describe the step-by-step approach to solve any pattern printing problem.

Think about rows, columns, spaces, and the relationship with i and n.

Step 1: Count total rows (determines outer loop from 1 to n). Step 2: For each row, identify what is printed (spaces and characters). Step 3: Express the count of spaces and characters as a formula in terms of row number i and total rows n. Step 4: Write inner loop(s) for spaces and characters. Step 5: Verify by plugging in i=1 and i=n to check the first and last rows match expectations.

Question 13

Easy

What is the output?

for (int i = 1; i <= 5; i++) {
    if (i == 4) break;
    if (i == 2) continue;
    System.out.print(i + " ");
}

continue skips 2, break stops at 4.

1 3

Question 14

Medium

What is the output?

int n = 3;
for (int i = n; i >= 1; i--) {
    for (int j = 1; j <= i; j++) {
        System.out.print("* ");
    }
    System.out.println();
}

Inverted right triangle: row 1 has 3 stars, row 2 has 2, row 3 has 1.

* * *
* *
*

Question 15

Medium

What is the output?

for (int i = 1; i <= 4; i++) {
    for (int j = 1; j <= i; j++) {
        System.out.print(j + " ");
    }
    System.out.println();
}

Each row prints 1 through i.

1
1 2
1 2 3
1 2 3 4

Question 16

Hard

What is the output?

for (int i = 1; i <= 4; i++) {
    for (int j = 1; j <= i; j++) {
        System.out.print(i + " ");
    }
    System.out.println();
}

Each row prints the row number i, repeated i times.

1
2 2
3 3 3
4 4 4 4

Question 17

Hard

What is the output?

int n = 4;
for (int i = 0; i < n; i++) {
    for (int j = 0; j <= i; j++) {
        System.out.print((char)('A' + j) + " ");
    }
    System.out.println();
}

Character pattern: (char)('A' + 0) = 'A', (char)('A' + 1) = 'B', etc.

A
A B
A B C
A B C D

Mixed & Application Questions

Question 1

Easy

Print numbers 1 to 20, but skip multiples of 4 using continue.

Use continue when i % 4 == 0.

for (int i = 1; i <= 20; i++) {
    if (i % 4 == 0) continue;
    System.out.print(i + " ");
}

Question 2

Easy

Print the following right triangle pattern for n = 5 using numbers:

Outer loop for rows, inner loop j from 1 to i.

int n = 5;
for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= i; j++) {
        System.out.print(j + " ");
    }
    System.out.println();
}

Question 3

Medium

Print an inverted right triangle of stars for n = 5:

* * * * *
* * * *
* * *
* *
*

Row i prints (n - i + 1) stars.

int n = 5;
for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n - i + 1; j++) {
        System.out.print("* ");
    }
    System.out.println();
}

Question 4

Medium

Print a number pyramid for n = 5:

Each row has (n-i) leading spaces, then numbers 1 to i.

int n = 5;
for (int i = 1; i <= n; i++) {
    for (int s = 1; s <= n - i; s++) {
        System.out.print(" ");
    }
    for (int j = 1; j <= i; j++) {
        System.out.print(j + " ");
    }
    System.out.println();
}

Question 5

Medium

What is the output?

for (int i = 5; i >= 1; i--) {
    for (int j = 1; j <= i; j++) {
        System.out.print(j + " ");
    }
    System.out.println();
}

i counts down from 5 to 1. Inner loop prints 1 to i.

1 2 3 4 5
1 2 3 4
1 2 3
1 2
1

Question 6

Medium

Print a hollow rectangle of stars with width 6 and height 4.

Print stars on first/last row and first/last column. Spaces elsewhere.

int rows = 4, cols = 6;
for (int i = 1; i <= rows; i++) {
    for (int j = 1; j <= cols; j++) {
        if (i == 1 || i == rows || j == 1 || j == cols) {
            System.out.print("* ");
        } else {
            System.out.print("  ");
        }
    }
    System.out.println();
}

Question 7

Easy

Print the following right triangle number pattern for n = 4:

Row i prints the number i, repeated i times.

int n = 4;
for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= i; j++) {
        System.out.print(i + " ");
    }
    System.out.println();
}

Question 8

Medium

Print a right-aligned number triangle for n = 4:

Row i has (n-i) spaces then numbers from i down to 1.

int n = 4;
for (int i = 1; i <= n; i++) {
    for (int s = 1; s <= n - i; s++) System.out.print("  ");
    for (int j = i; j >= 1; j--) System.out.print(j + " ");
    System.out.println();
}

Question 9

Hard

Print a sandglass pattern for n = 5:

* * * * *
 * * * *
  * * *
   * *
    *
   * *
  * * *
 * * * *
* * * * *

Upper half: inverted pyramid. Lower half: pyramid. Each row i has i-1 spaces then (n-i+1) or (i) stars.

int n = 5;
for (int i = 0; i < n; i++) {
    for (int s = 0; s < i; s++) System.out.print(" ");
    for (int j = 0; j < n - i; j++) System.out.print("* ");
    System.out.println();
}
for (int i = 1; i < n; i++) {
    for (int s = 0; s < n - i - 1; s++) System.out.print(" ");
    for (int j = 0; j <= i; j++) System.out.print("* ");
    System.out.println();
}

Question 10

Hard

Print the following butterfly pattern for n = 4:

*      *
**    **
***  ***
********
********
***  ***
**    **
*      *

Upper half: i stars, (2n - 2i) spaces, i stars. Lower half: mirror.

int n = 4;
// Upper half
for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= i; j++) System.out.print("*");
    for (int j = 1; j <= 2 * (n - i); j++) System.out.print(" ");
    for (int j = 1; j <= i; j++) System.out.print("*");
    System.out.println();
}
// Lower half
for (int i = n; i >= 1; i--) {
    for (int j = 1; j <= i; j++) System.out.print("*");
    for (int j = 1; j <= 2 * (n - i); j++) System.out.print(" ");
    for (int j = 1; j <= i; j++) System.out.print("*");
    System.out.println();
}

Question 11

Hard

Print a number diamond for n = 4:

Each row prints numbers ascending then descending. Use spaces for alignment.

int n = 4;
// Upper half
for (int i = 1; i <= n; i++) {
    for (int s = 1; s <= n - i; s++) System.out.print(" ");
    for (int j = 1; j <= i; j++) System.out.print(j);
    for (int j = i - 1; j >= 1; j--) System.out.print(j);
    System.out.println();
}
// Lower half
for (int i = n - 1; i >= 1; i--) {
    for (int s = 1; s <= n - i; s++) System.out.print(" ");
    for (int j = 1; j <= i; j++) System.out.print(j);
    for (int j = i - 1; j >= 1; j--) System.out.print(j);
    System.out.println();
}

Question 12

Hard

Print Pascal's triangle for n = 5 rows.

Each element = previous * (row - col) / (col + 1) using 0-indexed.

int n = 5;
for (int i = 0; i < n; i++) {
    for (int s = 0; s < n - i - 1; s++) System.out.print("  ");
    int val = 1;
    for (int j = 0; j <= i; j++) {
        System.out.printf("%4d", val);
        val = val * (i - j) / (j + 1);
    }
    System.out.println();
}

Multiple Choice Questions

MCQ 1

What does the break statement do inside a loop?

A. Skips the current iteration
B. Exits the innermost loop or switch
C. Exits the entire program
D. Pauses the loop

Answer: B
B is correct. break terminates the innermost enclosing loop or switch statement.

MCQ 2

What does the continue statement do?

A. Exits the loop
B. Restarts the loop from the beginning
C. Skips to the next iteration
D. Does nothing

Answer: C
C is correct. continue skips the remaining body of the current iteration and proceeds to the next iteration.

MCQ 3

What is a labeled break used for?

A. Breaking out of a switch
B. Breaking out of an outer loop from an inner loop
C. Giving a name to a break point
D. Debugging purposes

Answer: B
B is correct. A labeled break allows you to exit an outer loop from within an inner loop. The label is placed before the outer loop.

MCQ 4

In a right triangle star pattern of n rows, how many stars does row i have?

A. n
B. i
C. n - i
D. n - i + 1

Answer: B
B is correct. In a right triangle, row 1 has 1 star, row 2 has 2 stars, ..., row i has i stars.

MCQ 5

In a pyramid pattern of n rows, how many leading spaces does row i have?

A. i
B. n
C. n - i
D. 2 * i

Answer: C
C is correct. In a pyramid, row 1 has (n-1) spaces, row 2 has (n-2), ..., row i has (n-i) spaces.

MCQ 6

In a pyramid of n rows, how many stars does row i have?

A. i
B. 2 * i
C. 2 * i - 1
D. 2 * i + 1

Answer: C
C is correct. Row 1: 1 star, Row 2: 3, Row 3: 5. The formula is 2*i - 1 (odd numbers).

MCQ 7

What is Floyd's triangle?

A. An equilateral triangle of stars
B. A triangle where consecutive natural numbers fill the rows
C. A triangle where each row repeats its row number
D. A triangle of prime numbers

Answer: B
B is correct. Floyd's triangle fills rows with consecutive natural numbers: 1 / 2 3 / 4 5 6 / ... Row i has i numbers.

MCQ 8

What does return do inside a loop in a method?

A. Exits only the loop
B. Exits the entire method
C. Exits all nested loops but stays in the method
D. Causes a compilation error

Answer: B
B is correct. return exits the entire method, not just the loop. If the method has a return type, you must return a value.

MCQ 9

How many total stars are printed in a pyramid of n rows?

A. n * n
B. n * (n + 1) / 2
C. n^2
D. 2 * n - 1

Answer: C
C is correct. Row i has (2i-1) stars. Total = sum of (2i-1) for i=1 to n = 2 * n*(n+1)/2 - n = n^2.

MCQ 10

In Pascal's triangle, what is the value of the element at row 4, column 2 (0-indexed)?

A. 3
B. 4
C. 6
D. 10

Answer: C
C is correct. C(4,2) = 4! / (2! * 2!) = 24 / 4 = 6. Pascal's row 4 is: 1, 4, 6, 4, 1.

MCQ 11

What is the output?
outer: for (int i=0; i<3; i++) { for (int j=0; j<3; j++) { if (j==1) break; } System.out.print(i); }

A. 012
B. 000
C. 0
D. Nothing prints

Answer: A
A is correct. The inner break (without label) exits only the inner loop. The outer loop continues, printing i values: 0, 1, 2.

MCQ 12

What is a diamond pattern's total number of rows for n = 5 (upper half)?

A. 5
B. 9
C. 10
D. 8

Answer: B
B is correct. A diamond with n = 5 has n rows in the upper half and n-1 rows in the lower half. Total = n + (n-1) = 2n - 1 = 9.

MCQ 13

What is the correct syntax for a labeled break?

A. break label;
B. break(label);
C. break -> label;
D. exit label;

Answer: A
A is correct. Labeled break syntax is break labelName; where the label is declared before the loop as labelName:.

MCQ 14

In a right triangle of n rows, what is the total number of stars printed?

A. n * n
B. n * (n + 1) / 2
C. 2 * n
D. n * (n - 1) / 2

Answer: B
B is correct. Row 1 has 1 star, row 2 has 2, ..., row n has n. Total = 1 + 2 + ... + n = n(n+1)/2.

MCQ 15

What is the output?
for (int i = 1; i <= 3; i++) { for (int j = 1; j <= 3; j++) { if (i + j > 4) break; System.out.print(i+""+j+" "); } }

A. 11 12 13 21 22 23 31 32 33
B. 11 12 13 21 22 31
C. 11 12 21
D. 11 12 13 21 22 23 31

Answer: B
B is correct. i=1: j=1(11), j=2(12), j=3(13, 1+3=4 not >4 so prints). i=2: j=1(21), j=2(22), j=3(2+3=5>4, break inner). i=3: j=1(31, 3+1=4 not >4), j=2(3+2=5>4, break inner). Output: 11 12 13 21 22 31.

Coding Challenges

Challenge 1: Right-Aligned Star Triangle

Easy

Print a right-aligned triangle for n = 5:

    *
   **
  ***
 ****
*****

Sample Input

n = 5

Sample Output

* ** *** **** *****

Use spaces for alignment.

int n = 5;
for (int i = 1; i <= n; i++) {
    for (int s = 1; s <= n - i; s++) System.out.print(" ");
    for (int j = 1; j <= i; j++) System.out.print("*");
    System.out.println();
}

Challenge 2: Hollow Pyramid

Medium

Print a hollow pyramid for n = 5. Only the border stars are printed; interior is spaces.

Sample Input

n = 5

Sample Output

* * * * * * * *********

Print star on first column, last column, and last row. Spaces elsewhere.

int n = 5;
for (int i = 1; i <= n; i++) {
    for (int s = 1; s <= n - i; s++) System.out.print(" ");
    for (int j = 1; j <= 2 * i - 1; j++) {
        if (j == 1 || j == 2 * i - 1 || i == n) {
            System.out.print("*");
        } else {
            System.out.print(" ");
        }
    }
    System.out.println();
}

Challenge 3: Hourglass Pattern

Medium

Print an hourglass (inverted pyramid followed by a pyramid) for n = 5.

Sample Input

n = 5

Sample Output

********* ******* ***** *** * *** ***** ******* *********

Combine inverted pyramid (top) and pyramid (bottom).

int n = 5;
for (int i = n; i >= 1; i--) {
    for (int s = 1; s <= n - i; s++) System.out.print(" ");
    for (int j = 1; j <= 2 * i - 1; j++) System.out.print("*");
    System.out.println();
}
for (int i = 2; i <= n; i++) {
    for (int s = 1; s <= n - i; s++) System.out.print(" ");
    for (int j = 1; j <= 2 * i - 1; j++) System.out.print("*");
    System.out.println();
}

Challenge 4: Zigzag Number Pattern

Medium

Print a number pattern where odd rows go left-to-right and even rows go right-to-left:

Sample Input

n = 4

Sample Output

1 3 2 4 5 6 10 9 8 7

Track a global counter. For even rows, store numbers and print in reverse.

int n = 4;
int num = 1;
for (int i = 1; i <= n; i++) {
    int[] row = new int[i];
    for (int j = 0; j < i; j++) {
        row[j] = num++;
    }
    if (i % 2 == 0) {
        for (int j = i - 1; j >= 0; j--) System.out.print(row[j] + " ");
    } else {
        for (int j = 0; j < i; j++) System.out.print(row[j] + " ");
    }
    System.out.println();
}

Challenge 5: Star Diamond

Medium

Print a full diamond for n = 5 (upper half rows).

Sample Input

n = 5

Sample Output

* *** ***** ******* ********* ******* ***** *** *

Combine pyramid (upper) and inverted pyramid (lower, skip middle).

int n = 5;
for (int i = 1; i <= n; i++) {
    for (int s = 1; s <= n - i; s++) System.out.print(" ");
    for (int j = 1; j <= 2 * i - 1; j++) System.out.print("*");
    System.out.println();
}
for (int i = n - 1; i >= 1; i--) {
    for (int s = 1; s <= n - i; s++) System.out.print(" ");
    for (int j = 1; j <= 2 * i - 1; j++) System.out.print("*");
    System.out.println();
}

Challenge 6: Alphabet Diamond

Hard

Print a character diamond for n = 5:

    A
   ABA
  ABCBA
 ABCDCBA
ABCDEDCBA
 ABCDCBA
  ABCBA
   ABA
    A

Sample Input

n = 5

Sample Output

A ABA ABCBA ABCDCBA ABCDEDCBA ABCDCBA ABCBA ABA A

Each row: spaces, characters A to A+i-1, then back to A.

int n = 5;
for (int i = 1; i <= n; i++) {
    for (int s = 1; s <= n - i; s++) System.out.print(" ");
    for (int j = 0; j < i; j++) System.out.print((char)('A' + j));
    for (int j = i - 2; j >= 0; j--) System.out.print((char)('A' + j));
    System.out.println();
}
for (int i = n - 1; i >= 1; i--) {
    for (int s = 1; s <= n - i; s++) System.out.print(" ");
    for (int j = 0; j < i; j++) System.out.print((char)('A' + j));
    for (int j = i - 2; j >= 0; j--) System.out.print((char)('A' + j));
    System.out.println();
}

Challenge 7: Spiral Number Pattern

Hard

Print an n x n matrix filled with numbers 1 to n*n in spiral order. n = 4:

 1  2  3  4
12 13 14  5
11 16 15  6
10  9  8  7

Sample Input

n = 4

Sample Output

1 2 3 4 12 13 14 5 11 16 15 6 10 9 8 7

Use a 2D array and fill in spiral order: right, down, left, up.

int n = 4;
int[][] matrix = new int[n][n];
int num = 1, top = 0, bottom = n-1, left = 0, right = n-1;
while (num <= n * n) {
    for (int i = left; i <= right; i++) matrix[top][i] = num++;
    top++;
    for (int i = top; i <= bottom; i++) matrix[i][right] = num++;
    right--;
    for (int i = right; i >= left; i--) matrix[bottom][i] = num++;
    bottom--;
    for (int i = bottom; i >= top; i--) matrix[i][left] = num++;
    left++;
}
for (int[] row : matrix) {
    for (int val : row) System.out.printf("%3d", val);
    System.out.println();
}

Challenge 8: Pascal's Triangle (Print N Rows)

Hard

Print the first N rows of Pascal's triangle with proper alignment.

Sample Input

n = 6

Sample Output

1 1 1 1 2 1 1 3 3 1 1 4 6 4 1 1 5 10 10 5 1

Use the binomial coefficient formula iteratively.

int n = 6;
for (int i = 0; i < n; i++) {
    for (int s = 0; s < n - i - 1; s++) System.out.print("  ");
    int val = 1;
    for (int j = 0; j <= i; j++) {
        System.out.printf("%4d", val);
        val = val * (i - j) / (j + 1);
    }
    System.out.println();
}

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