Search in 2D Matrix in DSA Go - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if the matrix is empty.

DSA Go

if len(matrix) == [1] {
    return false
}

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A1

B-1

C0

Dlen(matrix[0])

Attempts:

3 left

💡 Hint

Common Mistakes

Checking len(matrix[0]) without verifying matrix is not empty.

Using 1 instead of 0 for empty check.

We check if the number of rows is zero to know if the matrix is empty.

2fill in blank

medium

Complete the code to get the number of columns in the matrix.

DSA Go

cols := len(matrix[1])

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A{0}

B0

C(0)

D[0]

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses or braces instead of square brackets.

Using len(matrix) instead of len(matrix[0]) for columns.

We use matrix[0] to access the first row and get its length for columns.

3fill in blank

hard

Fix the error in the binary search condition to find the target in a row.

DSA Go

for left <= right {
    mid := left + (right - left) / 2
    if matrix[row][mid] == [1] {
        return true
    } else if matrix[row][mid] < target {
        left = mid + 1
    } else {
        right = mid - 1
    }
}

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Amid

Btarget

Crow

Dleft

Attempts:

3 left

💡 Hint

Common Mistakes

Comparing with mid index instead of target value.

Using wrong variable names in condition.

The condition must compare the matrix element with the target value.

4fill in blank

hard

Fill both blanks to correctly perform binary search on the matrix rows.

DSA Go

for left, right := 0, [1] - 1; left <= right; {
    mid := left + (right - left) / 2
    if matrix[mid][0] == target {
        return true
    } else if matrix[mid][0] < [2] {
        left = mid + 1
    } else {
        right = mid - 1
    }
}

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Alen(matrix)

Btarget

Clen(matrix[0])

Dmid

Attempts:

3 left

💡 Hint

Common Mistakes

Using len(matrix[0]) for rows count.

Comparing with mid index instead of target.

We set right to last row index (len(matrix)-1) and compare matrix[mid][0] with target.

5fill in blank

hard

Fill all three blanks to complete the function that searches target in the 2D matrix.

DSA Go

func searchMatrix(matrix [][]int, target int) bool {
    if len(matrix) == 0 || len(matrix[1]) == 0 {
        return false
    }
    rows, cols := len(matrix), len(matrix[0])
    left, right := 0, rows - 1
    for left <= right {
        mid := left + (right - left) / 2
        if matrix[mid][0] == [2] {
            return true
        } else if matrix[mid][0] < target {
            left = mid + 1
        } else {
            right = mid - 1
        }
    }
    row := right
    if row < 0 {
        return false
    }
    left, right = 0, cols - 1
    for left <= right {
        mid := left + (right - left) / 2
        if matrix[row][mid] == target {
            return true
        } else if matrix[row][mid] < [3] {
            left = mid + 1
        } else {
            right = mid - 1
        }
    }
    return false
}

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A[0]

Btarget

Drow

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong index or variable in comparisons.

Not checking if matrix[0] exists before accessing.

Check if first row exists with matrix[0], compare matrix[mid][0] with target, and compare matrix[row][mid] with target.