[NeetCode150] Binary Search

Binary Search

Input: nums = [-1,0,3,5,9,12], target = 9
Output: 4
Explanation: 9 exists in nums and its index is 4

Binary Search

Input: nums = [-1,0,3,5,9,12], target = 9
Output: 4
Explanation: 9 exists in nums and its index is 4

easiest way is to use 2 pointers startIdx and endIdx, and check middleIdx

Search a 2D matrix

ou 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

think of the matrix as a 1D array, we have left = first item in matrix, right = last item in matrix. Find the middle item and use binary search to find target

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