53. Search a 2D Matrix II

Topic :

binary search

Difficulty :

medium

Problem Link :

problem statement

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.

Example 1:

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:

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:

m == matrix.length
n == matrix[i].length
1 <= n, m <= 300
-109 <= matrix[i][j] <= 109
All the integers in each row are sorted in ascending order.
All the integers in each column are sorted in ascending order.
-109 <= target <= 109

solution

import java.io.*;
import java.util.*;
class Search_in_a_2D_Matrix_II
{
   public static void main (String args[]){
    int [][] 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}}; 
    int target = 5;
    System.out.println(searchMatrix(matrix,target));
    }
   static boolean searchMatrix(int[][] matrix, int target) {
        int row=0;
        int col=matrix[0].length-1;
        
         while(row<matrix.length && col>=0){
            if(target==matrix[row][col])
                return true;
            else if(target>matrix[row][col])
                row++;
            else
                col--;
        }
        return false;
    } 
}