Calcule eficientemente sumas de diagonales de una array

Dada una array cuadrada 2D, encuentre la suma de los elementos en las diagonales Principal y Secundaria. Por ejemplo, considere la siguiente array de entrada de 4 X 4.

A00 A01 A02 A03
A10 A11 A12 A13
A20 A21 A22 A23
A30 A31 A32 A33

La diagonal primaria está formada por los elementos A00, A11, A22, A33. 

  1. Condición para la Diagonal Principal: La condición fila-columna es fila = columna. 
    La diagonal secundaria está formada por los elementos A03, A12, A21, A30.
  2. Condición para la diagonal secundaria: la condición fila-columna es fila = número de filas – columna -1.

Ejemplos: 

Input : 
4
1 2 3 4
4 3 2 1
7 8 9 6
6 5 4 3
Output :
Principal Diagonal: 16
Secondary Diagonal: 20

Input :
3
1 1 1
1 1 1
1 1 1
Output :
Principal Diagonal: 3
Secondary Diagonal: 3

Método 1: en este método, usamos dos bucles, es decir, un bucle para columnas y un bucle para filas y en el bucle interno verificamos la condición establecida anteriormente:

Implementación:

C++

// A simple C++ program to find sum of diagonals
#include <bits/stdc++.h>
using namespace std;
 
const int MAX = 100;
 
void printDiagonalSums(int mat[][MAX], int n)
{
    int principal = 0, secondary = 0;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
 
            // Condition for principal diagonal
            if (i == j)
                principal += mat[i][j];
 
            // Condition for secondary diagonal
            if ((i + j) == (n - 1))
                secondary += mat[i][j];
        }
    }
 
    cout << "Principal Diagonal:" << principal << endl;
    cout << "Secondary Diagonal:" << secondary << endl;
}
 
// Driver code
int main()
{
    int a[][MAX] = { { 1, 2, 3, 4 }, { 5, 6, 7, 8 },
                    { 1, 2, 3, 4 }, { 5, 6, 7, 8 } };
    printDiagonalSums(a, 4);
    return 0;
}

Java

// A simple java program to find
// sum of diagonals
import java.io.*;
 
public class GFG {
 
    static void printDiagonalSums(int [][]mat,
                                         int n)
    {
        int principal = 0, secondary = 0;
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
     
                // Condition for principal
                // diagonal
                if (i == j)
                    principal += mat[i][j];
     
                // Condition for secondary
                // diagonal
                if ((i + j) == (n - 1))
                    secondary += mat[i][j];
            }
        }
     
        System.out.println("Principal Diagonal:"
                                    + principal);
                                     
        System.out.println("Secondary Diagonal:"
                                    + secondary);
    }
 
    // Driver code
    static public void main (String[] args)
    {
         
        int [][]a = { { 1, 2, 3, 4 },
                      { 5, 6, 7, 8 },
                      { 1, 2, 3, 4 },
                      { 5, 6, 7, 8 } };
                     
        printDiagonalSums(a, 4);
    }
}
 
// This code is contributed by vt_m.

Python3

# A simple Python program to
# find sum of diagonals
MAX = 100
 
def printDiagonalSums(mat, n):
 
    principal = 0
    secondary = 0;
    for i in range(0, n):
        for j in range(0, n):
 
            # Condition for principal diagonal
            if (i == j):
                principal += mat[i][j]
 
            # Condition for secondary diagonal
            if ((i + j) == (n - 1)):
                secondary += mat[i][j]
         
    print("Principal Diagonal:", principal)
    print("Secondary Diagonal:", secondary)
 
# Driver code
a = [[ 1, 2, 3, 4 ],
     [ 5, 6, 7, 8 ],
     [ 1, 2, 3, 4 ],
      [ 5, 6, 7, 8 ]]
printDiagonalSums(a, 4)
 
# This code is contributed
# by ihritik

C#

// A simple C# program to find sum
// of diagonals
using System;
 
public class GFG {
 
    static void printDiagonalSums(int [,]mat,
                                        int n)
    {
        int principal = 0, secondary = 0;
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
     
                // Condition for principal
                // diagonal
                if (i == j)
                    principal += mat[i,j];
     
                // Condition for secondary
                // diagonal
                if ((i + j) == (n - 1))
                    secondary += mat[i,j];
            }
        }
     
        Console.WriteLine("Principal Diagonal:"
                                  + principal);
                                   
        Console.WriteLine("Secondary Diagonal:"
                                  + secondary);
    }
 
    // Driver code
    static public void Main ()
    {
        int [,]a = { { 1, 2, 3, 4 },
                     { 5, 6, 7, 8 },
                     { 1, 2, 3, 4 },
                     { 5, 6, 7, 8 } };
                      
        printDiagonalSums(a, 4);
    }
}
 
// This code is contributed by vt_m.

PHP

<?php
// A simple PHP program to
// find sum of diagonals
$MAX = 100;
 
function printDiagonalSums($mat, $n)
{
    global $MAX;
    $principal = 0;
    $secondary = 0;
    for ($i = 0; $i < $n; $i++)
    {
        for ($j = 0; $j < $n; $j++)
        {
 
            // Condition for
            // principal diagonal
            if ($i == $j)
                $principal += $mat[$i][$j];
 
            // Condition for
            // secondary diagonal
            if (($i + $j) == ($n - 1))
                $secondary += $mat[$i][$j];
        }
    }
 
    echo "Principal Diagonal:" ,
               $principal ,"\n";
    echo "Secondary Diagonal:",
              $secondary ,"\n";
}
 
// Driver code
$a = array (array ( 1, 2, 3, 4 ),
            array ( 5, 6, 7, 8 ),
            array ( 1, 2, 3, 4 ),
            array ( 5, 6, 7, 8 ));
printDiagonalSums($a, 4);
 
// This code is contributed by ajit
?>

Javascript

<script>
// A simple Javascript program to find sum of diagonals
 
const MAX = 100;
 
void printDiagonalSums(mat, n)
{
    let principal = 0, secondary = 0;
    for (let i = 0; i < n; i++) {
        for (let j = 0; j < n; j++) {
 
            // Condition for principal diagonal
            if (i == j)
                principal += mat[i][j];
 
            // Condition for secondary diagonal
            if ((i + j) == (n - 1))
                secondary += mat[i][j];
        }
    }
 
    document.write("Principal Diagonal:" + principal + "<br>");
    document.write("Secondary Diagonal:" + secondary + "<br>");
}
 
// Driver code
    let a = [ [ 1, 2, 3, 4 ], [ 5, 6, 7, 8 ],
                    [ 1, 2, 3, 4 ], [ 5, 6, 7, 8 ] ];
    printDiagonalSums(a, 4);
 
// This code is contributed by subhammahato348.
</script>
Producción

Principal Diagonal:18
Secondary Diagonal:18

Complejidad de tiempo : O(N*N) , ya que estamos usando bucles anidados para atravesar N*N veces.
Espacio auxiliar : O(1), ya que no estamos utilizando ningún espacio adicional.

Método 2 (enfoque eficiente): en este método usamos un bucle, es decir, un bucle para calcular la suma de las diagonales principal y secundaria: 

Implementación:

C++

// An efficient C++ program to find sum of diagonals
#include <bits/stdc++.h>
using namespace std;
 
const int MAX = 100;
 
void printDiagonalSums(int mat[][MAX], int n)
{
    int principal = 0, secondary = 0;
    for (int i = 0; i < n; i++) {
        principal += mat[i][i];
        secondary += mat[i][n - i - 1];       
    }
 
    cout << "Principal Diagonal:" << principal << endl;
    cout << "Secondary Diagonal:" << secondary << endl;
}
 
// Driver code
int main()
{
    int a[][MAX] = { { 1, 2, 3, 4 }, { 5, 6, 7, 8 },
                     { 1, 2, 3, 4 }, { 5, 6, 7, 8 } };
    printDiagonalSums(a, 4);
    return 0;
}

Java

// An efficient java program to find
// sum of diagonals
import java.io.*;
 
public class GFG {
 
    static void printDiagonalSums(int [][]mat,
                                        int n)
    {
        int principal = 0, secondary = 0;
        for (int i = 0; i < n; i++) {
            principal += mat[i][i];
            secondary += mat[i][n - i - 1];
        }
     
        System.out.println("Principal Diagonal:"
                                   + principal);
                                    
        System.out.println("Secondary Diagonal:"
                                   + secondary);
    }
     
    // Driver code
    static public void main (String[] args)
    {
        int [][]a = { { 1, 2, 3, 4 },
                      { 5, 6, 7, 8 },
                      { 1, 2, 3, 4 },
                      { 5, 6, 7, 8 } };
     
        printDiagonalSums(a, 4);
    }
}
 
// This code is contributed by vt_m.

Python3

# A simple Python3 program to find
# sum of diagonals
MAX = 100
 
def printDiagonalSums(mat, n):
 
    principal = 0
    secondary = 0
    for i in range(0, n):
        principal += mat[i][i]
        secondary += mat[i][n - i - 1]
         
    print("Principal Diagonal:", principal)
    print("Secondary Diagonal:", secondary)
 
# Driver code
a = [[ 1, 2, 3, 4 ],
     [ 5, 6, 7, 8 ],
     [ 1, 2, 3, 4 ],
     [ 5, 6, 7, 8 ]]
printDiagonalSums(a, 4)
 
# This code is contributed
# by ihritik

C#

// An efficient C#program to find
// sum of diagonals
using System;
 
public class GFG {
 
    static void printDiagonalSums(int [,]mat,
                                       int n)
    {
        int principal = 0, secondary = 0;
        for (int i = 0; i < n; i++) {
            principal += mat[i,i];
            secondary += mat[i,n - i - 1];
        }
     
        Console.WriteLine("Principal Diagonal:"
                                  + principal);
                                   
        Console.WriteLine("Secondary Diagonal:"
                                  + secondary);
    }
     
    // Driver code
    static public void Main ()
    {
        int [,]a = { { 1, 2, 3, 4 },
                     { 5, 6, 7, 8 },
                     { 1, 2, 3, 4 },
                     { 5, 6, 7, 8 } };
                      
        printDiagonalSums(a, 4);
    }
}
 
// This code is contributed by vt_m.

PHP

<?php
// An efficient PHP program
// to find sum of diagonals
$MAX = 100;
 
function printDiagonalSums($mat, $n)
{
    global $MAX;
    $principal = 0; $secondary = 0;
    for ($i = 0; $i < $n; $i++)
    {
        $principal += $mat[$i][$i];
        $secondary += $mat[$i][$n - $i - 1];    
    }
 
    echo "Principal Diagonal:" ,
               $principal ,"\n";
    echo "Secondary Diagonal:" ,
               $secondary ,"\n";
}
 
// Driver Code
$a = array(array(1, 2, 3, 4),
           array(5, 6, 7, 8),
           array(1, 2, 3, 4),
           array(5, 6, 7, 8));
printDiagonalSums($a, 4);
 
// This code is contributed by aj_36
?>

Javascript

<script>
 
// An efficient Javascript  program to find
// sum of diagonals
 
function  printDiagonalSums(mat,n)
    {
        let principal = 0, secondary = 0;
        for (let i = 0; i < n; i++) {
            principal += mat[i][i];
            secondary += mat[i][n - i - 1];
        }
     
        document.write("Principal Diagonal:"
                                + principal+"<br>");
                                     
        document.write("Secondary Diagonal:"
                                + secondary);
    }
     
    // Driver code
     
        let a = [[ 1, 2, 3, 4 ],
                    [5, 6, 7, 8 ],
                    [ 1, 2, 3, 4 ],
                    [ 5, 6, 7, 8 ]];
     
        printDiagonalSums(a, 4);
         
// This code is contributed Bobby
 
</script>
Producción

Principal Diagonal:18
Secondary Diagonal:18

Complejidad de tiempo: O (N), ya que estamos usando un bucle para atravesar N veces.
Espacio auxiliar: O(1) , ya que no estamos utilizando ningún espacio adicional.

Este artículo es una contribución de Mohak Agrawal . Si te gusta GeeksforGeeks y te gustaría contribuir, también puedes escribir un artículo usando write.geeksforgeeks.org o enviar tu artículo por correo a review-team@geeksforgeeks.org. Vea su artículo que aparece en la página principal de GeeksforGeeks y ayude a otros Geeks. 

Publicación traducida automáticamente

Artículo escrito por GeeksforGeeks-1 y traducido por Barcelona Geeks. The original can be accessed here. Licence: CCBY-SA

Deja una respuesta

Tu dirección de correo electrónico no será publicada. Los campos obligatorios están marcados con *