Please explain briefly

#1

INT TILING PROBLEM GIVEN IN COURSE,IF WE PLACE 1 TILE THEN TOTAL NUMBER OF WAYS is f(n-1) + f(n-4)…
how it is possible that if we place something then it is f(n-1) or
f(n-4)…
please explain briefly…

#2

@AMIT_KUMAR .u have tagged the wrong question .
for the tiling problem ,u can place a tile two ways vertical or horizontal.if u place a tile vertically it takes 1 space out of n so u are left with n - 1(occ by the vertical tile) space sowe can call f(n-1).if horizontal we ll have to place 4 tiles horizontally on top of each other.as the width of each tile is 4 , n-4 length is left now to be tiled so we can call f(n-4)