Is Toeplitz Matrix easy or hard?

Toeplitz Matrix is classified as an Easy problem on LeetCode with an acceptance rate around 69%. The challenge mainly tests your ability to recognize the diagonal relationship between matrix elements and implement a clean traversal.

How to solve Toeplitz Matrix in O(n)?

A full verification requires checking every element, so the overall complexity is O(m*n). The efficient trick is comparing each cell with matrix[i-1][j-1], which validates all diagonals in one pass without storing extra data.

What is the best approach for Toeplitz Matrix?

The best approach compares each element with its top-left neighbor while iterating through the matrix. If matrix[i][j] ever differs from matrix[i-1][j-1], the Toeplitz property breaks. This method runs in O(m*n) time with O(1) extra space and is the standard interview solution.

Is Toeplitz Matrix asked at Google/Amazon/Meta?

Toeplitz Matrix appears in coding interviews at companies that test matrix traversal and pattern recognition. Variants of this problem have shown up in interviews at Amazon, Google, and other large tech companies focusing on array and matrix fundamentals.

What data structure is used in Toeplitz Matrix?

The most efficient solution uses only the input matrix and simple index comparisons. An alternative solution uses a hash map keyed by (row - column) to track values belonging to the same diagonal.

What is the time complexity of Toeplitz Matrix?

The optimal solution runs in O(m*n) time where m is the number of rows and n is the number of columns. Each cell is visited exactly once and compared with its top-left neighbor. Space complexity is O(1) for the iterative method.

Toeplitz Matrix Python or Java solution approach?

Both Python and Java implementations typically use the same logic: iterate through the matrix starting from index (1,1) and compare each value with matrix[i-1][j-1]. This produces an O(m*n) time and O(1) space solution in either language.

Description Hints 1 Solution Video 8:16

766. Toeplitz Matrix

Easy69.8% acceptance4 companies

Given an m x n matrix, return true if the matrix is Toeplitz. Otherwise, return false.

A matrix is Toeplitz if every diagonal from top-left to bottom-right has the same elements.

Example 1:

Input: matrix = [[1,2,3,4],[5,1,2,3],[9,5,1,2]]
Output: true
Explanation:
In the above grid, the diagonals are:
"[9]", "[5, 5]", "[1, 1, 1]", "[2, 2, 2]", "[3, 3]", "[4]".
In each diagonal all elements are the same, so the answer is True.

Example 2:

Input: matrix = [[1,2],[2,2]]
Output: false
Explanation:
The diagonal "[1, 2]" has different elements.

Constraints:

m == matrix.length
n == matrix[i].length
1 <= m, n <= 20
0 <= matrix[i][j] <= 99

Follow up:

What if the matrix is stored on disk, and the memory is limited such that you can only load at most one row of the matrix into the memory at once?
What if the matrix is so large that you can only load up a partial row into the memory at once?