LeetCode-in-All

240. Search a 2D Matrix II

Medium

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

• Integers in each row are sorted in ascending from left to right.
• Integers in each column are sorted in ascending from top to bottom.

Example 1:

Input: matrix = [[1,4,7,11,15],[2,5,8,12,19],[3,6,9,16,22],[10,13,14,17,24],[18,21,23,26,30]], target = 5

Output: true

Example 2:

Input: matrix = [[1,4,7,11,15],[2,5,8,12,19],[3,6,9,16,22],[10,13,14,17,24],[18,21,23,26,30]], target = 20

Output: false

Constraints:

• m == matrix.length
• n == matrix[i].length
• 1 <= n, m <= 300
• -109 <= matrix[i][j] <= 109
• All the integers in each row are sorted in ascending order.
• All the integers in each column are sorted in ascending order.
• -109 <= target <= 109

Solution

func searchMatrix(matrix [][]int, target int) bool {
	r := 0
	c := len(matrix[0]) - 1
	for r < len(matrix) && c >= 0 {
		if matrix[r][c] == target {
			return true
		} else if matrix[r][c] > target {
			c--
		} else {
			r++
		}
	}
	return false
}

This site is open source. Improve this page.