# Day 21 of 30-Day LeetCode Challenge

## A binary matrix means that all elements are `0` or `1`. For each individual row of the matrix, this row is sorted in non-decreasing order.

Given a row-sorted binary matrix binaryMatrix, return leftmost column index(0-indexed) with at least a `1` in it. If such index doesn't exist, return `-1`.

You can’t access the Binary Matrix directly. You may only access the matrix using a `BinaryMatrix` interface:

• `BinaryMatrix.get(x, y)` returns the element of the matrix at index `(x, y)` (0-indexed).
• `BinaryMatrix.dimensions()` returns a list of 2 elements `[n, m]`, which means the matrix is `n * m`.

Submissions making more than `1000` calls to `BinaryMatrix.get` will be judged Wrong Answer. Also, any solutions that attempt to circumvent the judge will result in disqualification.

For custom testing purposes you’re given the binary matrix `mat` as input in the following four examples. You will not have access the binary matrix directly.

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