Find the first repeating element in an array of integers | Java program to find first repeating element in arr [ ] ; This function prints the first repeating element in arr [ ] ; Initialize index of first repeating element ; Creates an empty hashset ; Traverse the input array from right to left ; If element is already in hash set , update min ; Else add element to hash set ; Print the result ; Driver method to test above method
import java . util . * ; class Main { static void printFirstRepeating ( int arr [ ] ) { int min = - 1 ; HashSet < Integer > set = new HashSet < > ( ) ; for ( int i = arr . length - 1 ; i >= 0 ; i -- ) { if ( set . contains ( arr [ i ] ) ) min = i ; else set . add ( arr [ i ] ) ; } if ( min != - 1 ) System . out . println ( " The ▁ first ▁ repeating ▁ element ▁ is ▁ " + arr [ min ] ) ; else System . out . println ( " There ▁ are ▁ no ▁ repeating ▁ elements " ) ; } public static void main ( String [ ] args ) throws java . lang . Exception { int arr [ ] = { 10 , 5 , 3 , 4 , 3 , 5 , 6 } ; printFirstRepeating ( arr ) ; } }