Search a 2D Matrix

Search a 2D MatrixApr 7 '12

Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties:

• Integers in each row are sorted from left to right.
• The first integer of each row is greater than the last integer of the previous row.

For example,

Consider the following matrix:

[
  [1,   3,  5,  7],
  [10, 11, 16, 20],
  [23, 30, 34, 50]
]

Given target = 3, return true.

Analysis: The algorithm first finds the row to search by performing the binary search on the first column in log(m) time. Then that row is binary searched in log(n) time to return the result. log(m)+log(n) is the total time complexity.

An elegant solution