Find a common element in all rows of a given row | Java implementation of the approach ; Specify number of rows and columns ; Returns common element in all rows of mat [ M ] [ N ] . If there is no common element , then - 1 is returned ; A hash map to store count of elements ; Increment the count of first element of the row ; Starting from the second element of the current row ; If current element is different from the previous element i . e . it is appearing for the first time in the current row ; Find element having count equal to number of rows ; No such element found ; Driver Code
import java . util . * ; class GFG { static int M = 4 ; static int N = 5 ; static int findCommon ( int mat [ ] [ ] ) { HashMap < Integer , Integer > cnt = new HashMap < Integer , Integer > ( ) ; int i , j ; for ( i = 0 ; i < M ; i ++ ) { if ( cnt . containsKey ( mat [ i ] [ 0 ] ) ) { cnt . put ( mat [ i ] [ 0 ] , cnt . get ( mat [ i ] [ 0 ] ) + 1 ) ; } else { cnt . put ( mat [ i ] [ 0 ] , 1 ) ; } for ( j = 1 ; j < N ; j ++ ) { if ( mat [ i ] [ j ] != mat [ i ] [ j - 1 ] ) if ( cnt . containsKey ( mat [ i ] [ j ] ) ) { cnt . put ( mat [ i ] [ j ] , cnt . get ( mat [ i ] [ j ] ) + 1 ) ; } else { cnt . put ( mat [ i ] [ j ] , 1 ) ; } } } for ( Map . Entry < Integer , Integer > ele : cnt . entrySet ( ) ) { if ( ele . getValue ( ) == M ) return ele . getKey ( ) ; } return - 1 ; } public static void main ( String [ ] args ) { int mat [ ] [ ] = { { 1 , 2 , 3 , 4 , 5 } , { 2 , 4 , 5 , 8 , 10 } , { 3 , 5 , 7 , 9 , 11 } , { 1 , 3 , 5 , 7 , 9 } } ; int result = findCommon ( mat ) ; if ( result == - 1 ) System . out . println ( " No ▁ common ▁ element " ) ; else System . out . println ( " Common ▁ element ▁ is ▁ " + result ) ; } }