Search a 2D Matrix

You are given an `m x n` integer matrix `matrix` with the following two properties: - Each row is sorted in non-decreasing order. - The first integer of each row is greater than the last integer of the previous row. Given an integer `target`, return `true` _if_ `target` _is in_ `matrix` _or_ `false` _otherwise_. You must write a solution in `O(log(m * n))` time complexity.   **Example 1:** **Input:** matrix = [[1,3,5,7],[10,11,16,20],[23,30,34,60]], target = 3 **Output:** true ``` **Example 2:** **Input:** matrix = [[1,3,5,7],[10,11,16,20],[23,30,34,60]], target = 13 **Output:** false ```   **Constraints:** - `m == matrix.length` - `n == matrix[i].length` - `1 <= m, n <= 100` - `-104 <= matrix[i][j], target <= 104`