Description
Equilibrium index of an array is an index such that the sum of elements at lower indexes is equal to the sum of elements at higher indexes.
C Program
#include <stdio.h>
int Eqi_Index(int *arr, int n)
{
int i, j;
int l_sum, r_sum;
for (i = 0; i < n; ++i)
{
l_sum = 0;
for (j = 0; j < i; j++)
{
l_sum += arr[j];
}
r_sum = 0;
for (j = i + 1; j < n; j++)
{
r_sum += arr[j];
}
if (l_sum == r_sum)
{
return i;
}
}
return -1;
}
int main()
{
int n; scanf("%d",&n);
int arr[n];
for(int i = 0 ; i<n ; i++)
{
scanf("%d",&arr[i]);
}
printf("%d ",Eqi_Index(arr,n));
return 0;
}
C++ Program
#include <bits/stdc++.h>
using namespace std;
int Eqi_Index(int arr[], int n)
{
int i, j;
int l_sum, r_sum;
for (i = 0; i < n; ++i)
{
l_sum = 0;
for (j = 0; j < i; j++)
{
l_sum += arr[j];
}
r_sum = 0;
for (j = i + 1; j < n; j++)
{
r_sum += arr[j];
}
if (l_sum == r_sum)
{
return i;
}
}
return -1;
}
int main()
{
int n; cin>>n;
int arr[n];
for(int i = 0 ; i<n ; i++)
{
cin>>arr[i];
}
cout<<Eqi_Index(arr,n);
return 0;
}
JAVA Program
import java.util.*;
import java.lang.*;
import java.io.*;
class Main
{
public static int Eqi_Index(int arr[],int n)
{
int i, j;
int l_sum, r_sum;
for (i = 0; i < n; ++i)
{
l_sum = 0;
for (j = 0; j < i; j++)
{
l_sum += arr[j];
}
r_sum = 0;
for (j = i + 1; j < n; j++)
{
r_sum += arr[j];
}
if (l_sum == r_sum)
{
return i;
}
}
return -1;
}
public static void main (String[] args) throws java.lang.Exception
{
Scanner sc=new Scanner(System.in);
int size = sc.nextInt();
int[] arr = new int[size];
for(int i = 0 ; i<size ; i++)
{
arr[i] = sc.nextInt();
}
System.out.print(Eqi_Index(arr,size));
}
}
PYTHON Program
def Eqi_Index(arr):
l_sum = 0
r_sum = 0
n = len(arr)
for i in range(n):
l_sum = 0
r_sum = 0
for j in range(i):
l_sum += arr[j]
for j in range(i + 1, n):
r_sum += arr[j]
if l_sum == r_sum:
return i
return -1
arr = [10, 2, 4, 12]
print (Eqi_Index(arr))
