import java.util.*;
class TwoCanSum
{
public static void main(String args[])
{
// Create Scanner object
Scanner s=new Scanner(System.in);
// Take no.of elements
System.out.println("Enter the no.of elements");
int n=s.nextInt();
// Create an array of size n
int[] a=new int[n];
// Read the array
System.out.println("Enter the elements");
for(int i=0;i<n;i++)
{
a[i]=s.nextInt();
}
// Enter the target number
System.out.println("Enter the target number");
int target=s.nextInt();
// Check whether any two can sum
ArrayList<String> list=canSum(a,target);
// Get the size, don't call in loop
int size=list.size();
// Print the elements
for(int i=0;i<size;i++)
{
System.out.println(list.get(i));
}
}
public static ArrayList<String> canSum(int[] a,int target)
{
ArrayList<String> list=new ArrayList<String>();
for(int i=0;i<a.length;i++)
{
for(int j=i+1;j<a.length;j++)
{
if(a[i]+a[j]==target) list.add(a[i]+"+"+a[j]+"= "+target);
}
}
return list;
}
}
Sample output of the program
Enter the no.of elements
5
Enter the elements
9
6
7
2
8
Enter the target number
15
9+6= 15
7+8= 15
Explaining the logic of TwoCanSum
ArrayList<String> list=new ArrayList<String>(); Create an ArrayList<String>.
for(int i=0;i<a.length;i++) Loop a.length times where a is the array given as parameter. This loop gets the element at i.
for(int j=i+1;j<a.length;j++) The value of j will be i+1 and this loop is rotated until j equals a.length. When j equals length of the array, the loop breaks. This loop gets every element other than the element at i.
if(a[i]+a[j]==target) Check whether the element at index i and the element at index j sum up to give the target number. Enter the if block if this condition is satisfied else skip if-block.
list.add(a[i]+"+"+a[j]+"= "+target); Add the string which contains the value of the elements which can be summed to the target along with the target number preceded by an =.
Consider 5 elements, then the elements are checked for sum like,
a[0] checked with a[1],a[2],a[3],a[4]
a[1] checked with a[2],a[3],a[4]
......
return list; Returns the array list.
In this way, we can check whether two elements in an array can be summed to give the target number.