74. Search a 2D Matrix

Problem Link

Description

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You are given an m x n integer matrix matrix with the following two properties:

• Each row is sorted in non-decreasing order.
• The first integer of each row is greater than the last integer of the previous row.

Given an integer target, return true if target is in matrix or false otherwise.

You must write a solution in O(log(m * n)) time complexity.

 

Example 1:

Input: matrix = [[1,3,5,7],[10,11,16,20],[23,30,34,60]], target = 3
Output: true

Example 2:

Input: matrix = [[1,3,5,7],[10,11,16,20],[23,30,34,60]], target = 13
Output: false

 

Constraints:

• m == matrix.length
• n == matrix[i].length
• 1 <= m, n <= 100
• -104 <= matrix[i][j], target <= 104

Solution

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Python3

class Solution:
    def searchMatrix(self, matrix: List[List[int]], target: int) -> bool:
        rows, cols = len(matrix), len(matrix[0])
 
        left, right = 0, rows * cols
 
        while left < right:
            mid = left + (right - left) // 2
 
            x = matrix[mid // cols][mid % cols]
 
            if x >= target:
                right = mid
            else:
                left = mid + 1
        
        return left != rows * cols and matrix[left // cols][left % cols] == target