Block swap algorithm for array rotation |  ; Wrapper over the recursive function leftRotateRec ( ) It left rotates arr [ ] by d . ; Return If number of elements to be rotated is zero or equal to array size ; If number of elements to be rotated is exactly half of array size ; If A is shorter ; If B is shorter ; function to print an array ; This function swaps d elements starting at index fi with d elements starting at index si ; Driver Code
import java . util . * ; class GFG { public static void leftRotate ( int arr [ ] , int d , int n ) { leftRotateRec ( arr , 0 , d , n ) ; } public static void leftRotateRec ( int arr [ ] , int i , int d , int n ) { if ( d == 0 d == n ) return ; if ( n - d == d ) { swap ( arr , i , n - d + i , d ) ; return ; } if ( d < n - d ) { swap ( arr , i , n - d + i , d ) ; leftRotateRec ( arr , i , d , n - d ) ; } else { swap ( arr , i , d , n - d ) ; leftRotateRec ( arr , n - d + i , 2 * d - n , d ) ; } } public static void printArray ( int arr [ ] , int size ) { int i ; for ( i = 0 ; i < size ; i ++ ) System . out . print ( arr [ i ] + " ▁ " ) ; System . out . println ( ) ; } public static void swap ( int arr [ ] , int fi , int si , int d ) { int i , temp ; for ( i = 0 ; i < d ; i ++ ) { temp = arr [ fi + i ] ; arr [ fi + i ] = arr [ si + i ] ; arr [ si + i ] = temp ; } } public static void main ( String [ ] args ) { int arr [ ] = { 1 , 2 , 3 , 4 , 5 , 6 , 7 } ; leftRotate ( arr , 2 , 7 ) ; printArray ( arr , 7 ) ; } }