Pair of Numbers

C program to find presence of  pair of elements in array whose sum is equal to a given number.

#include<stdio.h>

int cmp(const void *a,const void *b)

{

return (*(int*)a-*(int*)b);

}

int main()

{

int n,i,x,j,flag=0;

printf("Enter the no. of elements in array:");

scanf("%d",&n);

int a[n];

printf("Enter the elements of array:");

for(i=0;i<n;i++)

scanf("%d",&a[i]);

printf("Enter the sum of Numbers:"); 

scanf("%d",&x);

qsort(a,n,sizeof(int),cmp);

i=0;j=n-1;

while(i<j)

{

if((a[i]+a[j])==x)

{

flag=1;

break;

}

else if((a[i]+a[j])>x) j--;

else if((a[i]+a[j])<x) i++;

}

if(flag)

printf("\nPresent");

else

printf("\nNot Present");

return 0;

}