for. T do. B end. for_xyz. T do. B end.The B block is evaluated once for each item of the array A that results from evaluating the T block. In the for_xyz. form, the local name xyz is set to the value of an item on each evaluation of the B block and xyz_index is set to the index of the item; results are not dependable if these names are re-assigned within the B block. break. goes to the end of the for. control structure, and continue. goes to the evaluation of B for the next item. |
f0=: 3 : 0 s=. 0 for. i. y do. s=.>:s end. ) (f0 = ])"0 ?5$100 1 1 1 1 1 f1=: 3 : 0 s=.0 for_j. i.y do. if. 2|j do. continue. end. s=.j+s end. ) (f1 = 2&!@>.&.-:)"0 ?5$100 1 1 1 1 1 comb=: 4 : 0 NB. All size x combinations of i.y k=. i.>:d=.y-x z=. (d$<i.0 0),<i.1 0 for. i.x do. z=. k ,.&.> ,&.>/\. >:&.> z end. ; z ) 3 comb 5 0 1 2 0 1 3 0 1 4 0 2 3 0 2 4 0 3 4 1 2 3 1 2 4 1 3 4 2 3 4 queens=: 3 : 0 NB. solves the n queens problem z=.i.n,*n=.y for. }.z do. b=. -. (i.n) e."1 ,. z +"1 _ ((-i.){:$z) */ _1 0 1 z=. ((+/"1 b)#z),.(,b)#(*/$b)$i.n end. ) queens 5 0 2 4 1 3 0 3 1 4 2 1 3 0 2 4 1 4 2 0 3 2 0 3 1 4 2 4 1 3 0 3 0 2 4 1 3 1 4 2 0 4 1 3 0 2 4 2 0 3 1