52. Search a 2D Matrix

Topic :

binary search

Difficulty :

medium

Problem Link :

link

problem statement

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

import java.io.*;
import java.util.*;
class Search_in_a_2D_Matrix
{
   public static void main (String args[]){
    int [][] matrix = {{1,3,5,7},{10,11,16,20},{23,30,34,60}}; 
    int target = 3;
    System.out.println(searchMatrix(matrix,target));
    }
     static boolean searchMatrix(int[][] matrix, int target) {
        
        if(matrix.length==0||matrix==null)
            return false;
        
        int n=matrix.length;
        int m=matrix[0].length;
        
        int low=0;
        int high=(n*m)-1;
        
        while (low<=high)
        {
            int mid=(low+high)/2;
            
            if(matrix[mid/m][mid%m]==target)
                return true;
            
            if(matrix[mid/m][mid%m]<target)
                low=mid+1;
            else 
                high=mid-1;
        }
        return false;
        
    }
}