[LeetCode] Search a 2D Matrix

[LeetCode] Search a 2D Matrix
 

Search a 2D Matrix

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 from left to right.
• The first integer of each row is greater than the last integer of the previous row.

   

  For example,

  Consider the following matrix:

  [  [1,   3,  5,  7],  [10, 11, 16, 20],  [23, 30, 34, 50]]

  Given target =3, Returntrue.

Solution:

Define a matrix and a target value to determine whether the target value exists in the matrix. Matrix satisfied: each row increments from left to right, and the first element of the next row is greater than the last element of the previous row.

You can use the Binary Search Method to convert one-dimensional coordinates into two-dimensional coordinates.

 

Class Solution {public: bool searchMatrix (vector
 
  
> & Matrix, int target) {// binary search, converts a matrix query to a linear query int m = matrix. size (); if (m = 0) {return false;} int n = matrix [0]. size (); if (n = 0) {return false;} int start = 0, end = m * n-1; while (start <= end) {int middle = (start + end)/2; int x = middle/n; int y = middle % n; if (matrix [x] [y] = target) {return true;} else if (matrix [x] [y]