Q. Write an algorithm and program to find all pairs of elements in an integer array whose sum is equal to a given number.

Solution : You are given an array and a number and task is to find all pairs of elements in an integer array whose sum is equal to a given number.

Array :- An array is a collection of data items, all of the same type, accessed using a common name.
For example: int arr[5]={1,2,3,4,5};

Algorithm to find pairs of elements in an integer array

//Algorithm To Find All Pairs Of Elements In An Integer Array.
START
Step 1 ->  Input ARRAY arr[] and NUMBER num.
Step 2 ->  for i=0 to length of the arr[]-1:
for j=i+1 to length of the arr[]:
if arr[i]+arr[j] equals to num:
print the output
Loop End
Loop End
STOP


Program to find all pairs of elements in an integer array

  • C
  • C++
  • Java
  • Python
  • C#
  • PHP
    • //C Program To Find All Pairs Of Elements In An Integer Array.
#include <stdio.h>
int main()
{
int arr[7]={4, 6, 8, 10, 12, 14, 16};
int num=18;
for(int i=0;i<6;i++)
{
for(int j=i+1;j<7;j++)
{
if((arr[i]+arr[j])==num)
{
printf("%d + %d = %d\n",arr[i],arr[j],num);
}
}
}
return 0;
}

    //C++ Program To Find All Pairs Of Elements In An Integer Array.
#include <iostream>
using namespace std;
int main()
{
int arr[7]={4, 6, 8, 10, 12, 14, 16};
int num=18;
for(int i=0;i<6;i++)
{
for(int j=i+1;j<7;j++)
{
if((arr[i]+arr[j])==num)
{
cout<<arr[i]<<" + "<<arr[j]<<" = "<<num<<"\n";
}
}
}
return 0;
} 
    //Java Program To Find All Pairs Of Elements In An Integer Array.
import java.util.Arrays;
public class Main
{
public static void main(String[] args)
{
int arr[] = { 4, 6, 8, 10, 12, 14, 16 }; 
int num = 18; 
for(int i=0;i<6;i++)
{
for(int j=i+1;j<7;j++)
{
if((arr[i]+arr[j])==num)
{
System.out.println(arr[i]+" + "+arr[j]+" = "+num);
}
}
}
}
}

    //Python Program To Find All Pairs Of Elements In An Integer Array.
arr = [ 4, 6, 8, 10, 12, 14, 16 ]
n = len(arr)
num = 18
for i in range(0, n): 
for j in range(i+1, n):
if((arr[i]+arr[j])==num):
print(arr[i]," + ",arr[j]," = ",num) 

    //C# Program To Find All Pairs Of Elements In An Integer Array.
using System;
class LFC {
static void Main() {
int[] arr = { 4, 6, 8, 10, 12, 14, 16 }; 
int num = 18;
for(int i=0;i<6;i++)
{
for(int j=i+1;j<7;j++)
{
if((arr[i]+arr[j])==num)
{
Console.WriteLine(arr[i]+" + "+arr[j]+" = "+num);
}
}
}
}
} 
    //PHP Program To Find All Pairs Of Elements In An Integer Array.
<?php
$arr = array(4, 6, 8, 10, 12, 14, 16); 
$num = 18; 
for($i=0;$i<6;$i++)
{
for($j=$i+1;$j<7;$j++)
{
if(($arr[$i]+$arr[$j])==$num)
{
echo "$arr[$i] + $arr[$j] = $num\n";
}
}
}?>
    //C Program To Find All Pairs Of Elements In An Integer Array.
#include <stdio.h>
int main()
{
int arr[7]={4, 6, 8, 10, 12, 14, 16};
int num=18;
for(int i=0;i<6;i++)
{
for(int j=i+1;j<7;j++)
{
if((arr[i]+arr[j])==num)
{
printf("%d + %d = %d\n",arr[i],arr[j],num);
}
}
}
return 0;
}

    Output

    4 + 14 = 18
6 + 12 = 18
8 + 10 = 18

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