# Repeating Elements

Tue Feb 08 2022 14:28:19 GMT+0000 (Coordinated Universal Time)

```// Method-2 : Time Complexity : O(n),  Auxiliary Space : O(1)

import java.util.*;
import java.io.*;

class GFG
{

static int repeat(int arr[], int n)
{
int slow = arr[0], fast = arr[0];

do{
slow = arr[slow];
fast = arr[arr[fast]];

}while(slow != fast);

slow = arr[0];

while(slow != fast)
{
slow = arr[slow];
fast = arr[fast];
}
return slow;
}

public static void main(String args[])
{
int arr[] = {1, 3, 2, 4, 6, 5, 7, 3}, n= 8;

System.out.println(repeat(arr, n));     // OUTPUT : 3
}

}

// Method-1 : Time Complexity : O(n),  Auxiliary Space : O(n)

import java.util.*;
import java.io.*;

class GFG
{
static int repeat(int arr[], int n)
{
boolean visit[] = new boolean[n];

for(int i = 0; i < n; i++)
{
if(visit[arr[i]])
return arr[i];
visit[arr[i]] = true;
}

return -1;
}

public static void main(String args[])
{
int arr[] = {0, 2, 1, 3, 2, 2}, n= 6;

System.out.println(repeat(arr, n));     // OUTPUT : 2
}

}```
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