Printing Boundary Elements of a Matrix.
Examples:
Input : 1 2 3 4
5 6 7 8
1 2 3 4
5 6 7 8
Output : 1 2 3 4
5 8
1 4
5 6 7 8
The idea is really simple. We traverse given matrix. For every element being traversed, we print it if it is a corner element. If it is not a corner element, then we print space character.
C++
#include <bits/stdc++.h>
using namespace std;
const int MAX = 100;
void printBoundary(int a[][MAX], int m, int n)
{
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
if (i == 0 || j == 0 || i == n - 1 || j == n - 1)
cout << a[i][j] << " ";
else
cout << " "
<< " ";
}
cout << "
";
}
}
int main()
{
int a[4][MAX] = { { 1, 2, 3, 4 }, { 5, 6, 7, 8 }, { 1, 2, 3, 4 }, { 5, 6, 7, 8 } };
printBoundary(a, 4, 4);
return 0;
}
|
Java
class GFG {
public static void printBoundary(int a[][], int m,
int n)
{
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
if (i == 0)
System.out.print(a[i][j] + " ");
else if (i == m - 1)
System.out.print(a[i][j] + " ");
else if (j == 0)
System.out.print(a[i][j] + " ");
else if (j == n - 1)
System.out.print(a[i][j] + " ");
else
System.out.print(" ");
}
System.out.println("");
}
}
public static void main(String[] args)
{
int a[][] = { { 1, 2, 3, 4 }, { 5, 6, 7, 8 }, { 1, 2, 3, 4 }, { 5, 6, 7, 8 } };
printBoundary(a, 4, 4);
}
}
|
Python
MAX = 100
def printBoundary(a, m, n):
for i in range(m):
for j in range(n):
if (i == 0):
print a[i][j],
elif (i == m-1):
print a[i][j],
elif (j == 0):
print a[i][j],
elif (j == n-1):
print a[i][j],
else:
print " ",
print
a = [ [ 1, 2, 3, 4 ], [ 5, 6, 7, 8 ],
[ 1, 2, 3, 4 ], [ 5, 6, 7, 8 ] ]
printBoundary(a, 4, 4)
|
C#
using System;
class GFG {
public static void printBoundary(int[, ] a,
int m,
int n)
{
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
if (i == 0)
Console.Write(a[i, j] + " ");
else if (i == m - 1)
Console.Write(a[i, j] + " ");
else if (j == 0)
Console.Write(a[i, j] + " ");
else if (j == n - 1)
Console.Write(a[i, j] + " ");
else
Console.Write(" ");
}
Console.WriteLine(" ");
}
}
static public void Main()
{
int[, ] a = { { 1, 2, 3, 4 },
{ 5, 6, 7, 8 },
{ 1, 2, 3, 4 },
{ 5, 6, 7, 8 } };
printBoundary(a, 4, 4);
}
}
|
PHP
<?php
$MAX = 100;
function printBoundary($a, $m, $n)
{
global $MAX;
for ($i = 0; $i < $m; $i++)
{
for ($j = 0; $j < $n; $j++)
{
if ($i == 0)
echo $a[$i][$j], " ";
else if ($i == $m - 1)
echo $a[$i][$j], " ";
else if ($j == 0)
echo $a[$i][$j], " ";
else if ($j == $n - 1)
echo $a[$i][$j], " ";
else
echo " ", " ";
}
echo "
";
}
}
$a = array(array( 1, 2, 3, 4 ),
array( 5, 6, 7, 8 ),
array( 1, 2, 3, 4 ),
array( 5, 6, 7, 8 ));
printBoundary($a, 4, 4);
?>
|
Output:
1 2 3 4
5 8
1 4
5 6 7 8
Finding sum of boundary elements
Examples:
Input : 1 2 3 4
5 6 7 8
1 2 3 4
5 6 7 8
Output : 54
C++
#include <bits/stdc++.h>
using namespace std;
const int MAX = 100;
int getBoundarySum(int a[][MAX], int m, int n)
{
long long int sum = 0;
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
if (i == 0)
sum += a[i][j];
else if (i == m - 1)
sum += a[i][j];
else if (j == 0)
sum += a[i][j];
else if (j == n - 1)
sum += a[i][j];
}
}
return sum;
}
int main()
{
int a[][MAX] = { { 1, 2, 3, 4 }, { 5, 6, 7, 8 }, { 1, 2, 3, 4 }, { 5, 6, 7, 8 } };
long long int sum = getBoundarySum(a, 4, 4);
cout << "Sum of boundary elements is " << sum;
return 0;
}
|
Java
class GFG {
public static long getBoundarySum(int a[][], int m,
int n)
{
long sum = 0;
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
if (i == 0)
sum += a[i][j];
else if (i == m - 1)
sum += a[i][j];
else if (j == 0)
sum += a[i][j];
else if (j == n - 1)
sum += a[i][j];
}
}
return sum;
}
public static void main(String[] args)
{
int a[][] = { { 1, 2, 3, 4 }, { 5, 6, 7, 8 }, { 1, 2, 3, 4 }, { 5, 6, 7, 8 } };
long sum = getBoundarySum(a, 4, 4);
System.out.println("Sum of boundary elements"
+ " is " + sum);
}
}
|
Python
MAX = 100
def printBoundary(a, m, n):
sum = 0
for i in range(m):
for j in range(n):
if (i == 0):
sum += a[i][j]
elif (i == m-1):
sum += a[i][j]
elif (j == 0):
sum += a[i][j]
elif (j == n-1):
sum += a[i][j]
return sum
a = [ [ 1, 2, 3, 4 ], [ 5, 6, 7, 8 ],
[ 1, 2, 3, 4 ], [ 5, 6, 7, 8 ] ]
sum = printBoundary(a, 4, 4)
print "Sum of boundary elements is", sum
|
C#
using System;
class GFG {
public static long getBoundarySum(int[, ] a,
int m, int n)
{
long sum = 0;
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
if (i == 0)
sum += a[i, j];
else if (i == m - 1)
sum += a[i, j];
else if (j == 0)
sum += a[i, j];
else if (j == n - 1)
sum += a[i, j];
}
}
return sum;
}
static public void Main()
{
int[, ] a = { { 1, 2, 3, 4 },
{ 5, 6, 7, 8 },
{ 1, 2, 3, 4 },
{ 5, 6, 7, 8 } };
long sum = getBoundarySum(a, 4, 4);
Console.WriteLine("Sum of boundary"
+ " elements is " + sum);
}
}
|
PHP
<?php
function getBoundarySum($a,
$m, $n)
{
$sum = 0;
for ($i = 0; $i < $m; $i++)
{
for ( $j = 0; $j < $n; $j++)
{
if ($i == 0)
$sum += $a[$i][$j];
else if ($i == $m - 1)
$sum += $a[$i][$j];
else if ($j == 0)
$sum += $a[$i][$j];
else if ($j == $n - 1)
$sum += $a[$i][$j];
}
}
return $sum;
}
$a = array(array(1, 2, 3, 4),
array(5, 6, 7, 8),
array(1, 2, 3, 4),
array(5, 6, 7, 8));
$sum = getBoundarySum($a, 4, 4);
echo "Sum of boundary elements is ", $sum;
?>
|
Output:
Sum of boundary elements is 54
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