Given a multi-dimensional 2D matrix of n rows and m column order N × M. The task is to find the maximum element in the given matrix.
Illustration:
Input : mat[][] = { {1,3,4,19}, {11,10,12,1}, {7,9,0,4,99} } Output : 99
Methods:
- Iterative method (naive approach)
- Using the principle of recursion (Bit more optimal approach)
Method 1: Iterative method
The approach is simple to iterate every element of the matrix one by one and store the maximum of two elements in the max variable as used below in the program and returns the max variable that contains the maximum element of the matrix.
Example
// Java Program to Find the Maximum Element in a Matrix // Importing input output classes import java.io.*;
// Main class class GFG {
// Method 1
// To find the maximum element
static int max( int mat[][])
{
// Declaring and initializing variable to unity
// holding the maximum element value
int max = 0 ;
// Iterating over matrix
// using nested for loops
// Outer loop for rows
for ( int i = 0 ; i < mat.length; ++i) {
// Inner loop for columns
for ( int j = 0 ; j < mat[ 0 ].length; ++j) {
// Storing the maximum element
max = Math.max(mat[i][j], max);
}
}
// Return the maximum element
return max;
}
// Method 2
// Main driver method
public static void main(String[] args)
{
// Custom input 2D matrix
int mat[][] = { { 1 , 3 , 4 , 19 },
{ 11 , 10 , 12 , 1 },
{ 7 , 9 , 0 , 99 } };
// Calling the method 1 to get max element
// and storing that integer element
int max_element = max(mat);
// Printing the maximum element
System.out.println(max_element);
}
} |
99
Time Complexity: O(n2)
Auxiliary Space: O(1)
Method 2: Using the principle of recursion
Procedure:
- Recursively call every element of the matrix to the last element of the matrix.
- Return the max of the current element to the next recursive call element.
Example
// Java Program to Find the Maximum Element in a Matrix // Using Recursion // Importing input output classes import java.io.*;
// main class class GFG {
// Method 1
// To find the max element
static int max( int mat[][], int i, int j)
{
// Handling the base cases
if (j == mat[ 0 ].length && i < mat.length) {
// Changing the row and column index
j = 0 ;
++i;
}
// Generic case
if (i == mat.length) {
// Simply return
return 0 ;
}
// By far if we reach here then
// return the max element
return Math.max(mat[i][j], max(mat, i, j + 1 ));
}
// Method 2
// Main driver method
public static void main(String[] args)
{
// Custom input 2D array
int mat[][] = { { 1 , 3 , 4 , 19 },
{ 11 , 10 , 12 , 1 },
{ 7 , 9 , 0 , 99 } };
// Calling the method 1 that is recursive function to
// find out maximum element
int max_element = max(mat, 0 , 0 );
// Print and display the maximum element
System.out.println(max_element);
}
} |
99
Time Complexity: O(n)
Auxiliary Space: O(n)