Search in 2D Matrix in DSA Javascript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start searching from the top-right corner of the matrix.

DSA Javascript

let row = 0;
let col = matrix[0].length [1] 1;

Drag options to blanks, or click blank then click option'

A+

B/

C*

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using + instead of - causes index out of range.

Using * or / is not correct for index calculation.

We start from the last column index, so we subtract 1 from the length.

2fill in blank

medium

Complete the code to move left when the current element is greater than the target.

DSA Javascript

if (matrix[row][col] > target) {
  col [1] 1;
}

Drag options to blanks, or click blank then click option'

A++

B+=

C-=

D--

Attempts:

3 left

💡 Hint

Common Mistakes

Using += increases the column index, moving right instead of left.

Using ++ or -- alone changes by 1 but does not assign.

We decrease the column index by 1 to move left.

3fill in blank

hard

Fix the error in the loop condition to prevent out-of-bound errors.

DSA Javascript

while (row < matrix.length && col [1] 0) {
  // search logic
}

Drag options to blanks, or click blank then click option'

A<

B>=

C<=

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using > 0 skips checking column 0.

Using < or <= causes logic errors in loop.

Column index must be greater than or equal to 0 to stay within bounds and check column 0.

4fill in blank

hard

Fill both blanks to correctly move down or left based on comparison.

DSA Javascript

if (matrix[row][col] < target) {
  row [1] 1;
} else {
  col [2] 1;
}

Drag options to blanks, or click blank then click option'

A+=

B-=

C++

D--

Attempts:

3 left

💡 Hint

Common Mistakes

Using -= to move down or += to move left is incorrect.

Using ++ or -- without assignment causes errors.

Increase row to move down, decrease col to move left.

5fill in blank

hard

Fill all three blanks to complete the search function returning true if target found, else false.

DSA Javascript

function searchMatrix(matrix, target) {
  let row = 0;
  let col = matrix[0].length [1] 1;
  while (row < matrix.length && col [2] 0) {
    if (matrix[row][col] === target) {
      return [3];
    } else if (matrix[row][col] < target) {
      row += 1;
    } else {
      col -= 1;
    }
  }
  return false;
}

Drag options to blanks, or click blank then click option'

A+

B>=

Ctrue

D-

E<

Ffalse

Attempts:

3 left

💡 Hint

Common Mistakes

Using + instead of - for last column index.

Using < or <= in loop condition causing errors.

Returning false instead of true when found.

Start from last column (length - 1), loop while col >= 0, return true if found.