Search Matrix

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.

Solution

class Solution(object):
    def searchMatrix(self, matrix, target):
        """
        :type matrix: List[List[int]]
        :type target: int
        :rtype: bool
        """
        if not matrix or target is None:
            return False
        rows, cols = len(matrix), len(matrix[0])
        low, high = 0, rows * cols - 1

        while low <= high:
            mid = (low + high) / 2
            num = matrix[mid / cols][mid % cols]

            if num == target:
                return True
            elif num < target:
                low = mid + 1
            else:
                high = mid - 1
        return False

public class Solution {
    public boolean searchMatrix(int[][] matrix, int target) {
        if(matrix == null || matrix.length < 1 || matrix[0].length <1) {
            return false;
        }

        int row = 0, col = matrix[0].length - 1;

        while(col >= 0 && row < matrix.length) {
            if(target == matrix[row][col])
                return true;
            else if(target > matrix[row][col])
                row++;
            else
                col--;
        }

        return false;
    }
}