Find the Missing Number | Java implementation ; a represents the array n : Number of elements in array a ; Driver Code
class GFG { static int getMissingNo ( int a [ ] , int n ) { int total = 1 ; for ( int i = 2 ; i <= ( n + 1 ) ; i ++ ) { total += i ; total -= a [ i - 2 ] ; } return total ; } public static void main ( String [ ] args ) { int [ ] arr = { 1 , 2 , 3 , 5 } ; System . out . println ( getMissingNo ( arr , arr . length ) ) ; } }