From 4c3b8a0335355d608685dbeffb4f378560a49840 Mon Sep 17 00:00:00 2001
From: juan <juancloudcomputing@protonmail.com>
Date: Sat, 3 Sep 2022 15:06:04 +0800
Subject: [PATCH] vault backup: 2022-09-03 15:06:04

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 .../pages/Leetcode Search-A-2D-Matrix-II.md   | 59 +++++++++++++++++++
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diff --git a/OJ notes/pages/Leetcode Search-A-2D-Matrix-II.md b/OJ notes/pages/Leetcode Search-A-2D-Matrix-II.md
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+# Leetcode Search-A-2D-Matrix-II
+
+2022-09-03 14:57
+
+> ##### Algorithms:
+> #algorithm #divide_and_conquer
+> ##### Data structures:
+> #DS #array 
+> ##### Difficulty:
+> #coding_problem #difficulty-medium
+> ##### Additional tags:
+> #leetcode 
+> ##### Revisions:
+> N/A
+
+##### Links:
+- [Link to problem](https://leetcode.com/problems/search-a-2d-matrix-ii/)
+___
+### Problem
+
+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.
+
+#### Examples
+
+**Example 1:**
+
+![](https://assets.leetcode.com/uploads/2020/11/24/searchgrid2.jpg)
+
+```
+**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:**
+
+![](https://assets.leetcode.com/uploads/2020/11/24/searchgrid.jpg)
+
+```
+**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
+
+### Thoughts
+
+> [!summary]
+> This is a #divide_and_conquer problem.
+
+It's divide and conquer, because every time we do a action, 
+the problem is smaller.
+
+Start from the top-right, (alternatively, bottom-left),
+because walking left makes the number smaller, and down makes the number bigger.
+
+### Solution