CODE 59: Search a 2D 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.

 

	public boolean searchMatrix(int[][] matrix, int target) {
		// Note: The Solution object is instantiated only once and is reused by
		// each test case.
		if (null == matrix || matrix.length <= 0) {
			return false;
		}
		int rows = matrix.length;
		int cols = matrix[0].length;
		int all = rows * cols;
		boolean finded = false;
		int i;
		for (i = 0; i < all - 1; i++) {
			if (matrix[i / cols][i % cols] > matrix[(i + 1) / cols][(i + 1)
					% cols]) {
				break;
			}
			if (matrix[i / cols][i % cols] == target) {
				finded = true;
			}
		}
		if (i < all - 1) {
			return false;
		} else if (matrix[rows - 1][cols - 1] == target) {
			finded = true;
		}
		return finded;
	}