MUYANG GUO / INDEX

LeetCode

LeetCode 240 Search A2 D Matrix II - Medium

240. Search a 2D Matrix II

·1 min read·#LeetCode#Medium#Python

240. Search A2 D Matrix II — Medium

Open on LeetCode

Problem

  1. Search a 2D Matrix II

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 in ascending from left to right. Integers in each column are sorted in ascending from top to bottom. Example:

Consider the following 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] ] Given target = 5, return true.

Given target = 20, return false.

Solution

### https://leetcode.com/problems/search-a-2d-matrix-ii/solution/
 
 
 
class Solution:
    def searchMatrix(self, matrix, target):
        """
        :type matrix: List[List[int]]
        :type target: int
        :rtype: bool
        """
        ### start from the top-right corner:
        m = len(matrix)
        if m == 0:
            return False
        n = len(matrix[0])
        if n == 0:
            return False
        
        x, y = 0, n - 1
        
        while x <= m - 1 and y >= 0:
            if matrix[x][y] == target:
                return True
            elif matrix[x][y] < target:
                x += 1
            else:
                y -= 1
        
        return False

Comments