# Program to find equilibrium index of an array

12 May 2023

12 May 2023

Write a program to find equilibrium index of an array

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## Description about Program to find equilibrium index of an array

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 to find equilibrium index of an array

#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 to find equilibrium index of an array???????

#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 to find equilibrium index of an array???????

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 to find equilibrium index of an array???????

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))

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