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240. Search a 2D Matrix II

Difficulty Topics

Description

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

search-a-2d-matrix-ii.py
class Solution:
    def searchMatrix(self, matrix: List[List[int]], target: int) -> bool:
        rows, cols = len(matrix), len(matrix[0])

        if not matrix or rows == 0 or cols == 0: return False

        row, col = 0, cols - 1

        while row < rows and col >= 0:
            curr = matrix[row][col]

            if curr == target: 
                return True
            elif curr > target: 
                col -= 1
            else:
                row += 1

        return False