git.zerfleddert.de Git - micropolis/blame_incremental - src/tclx/tcllib/8queens.tcl

#
# Eight Queens in Tcl
#
# by Karl Lehenbauer, 23 Nov 1990
#
#-----------------------------------------------------------------------------
# $Id: 8queens.tcl,v 2.0 1992/10/16 04:51:36 markd Rel $
#-----------------------------------------------------------------------------
#
proc none_attacking {rank position} {
    global queens
    loop i 1 $rank {
	set j $queens([expr {$rank - $i}])
	if {($j==$position-$i) || ($j==$position) || ($j==$position+$i)} {
	    return 0
	}
    }
    return 1
}

proc solution {} {
    global queens
    echo $queens(1) $queens(2) $queens(3) $queens(4) $queens(5) $queens(6) $queens(7) $queens(8)
}

proc x8queens {rank} {
    global queens
    set queens($rank) 1
    loop i 1 9 {
	if [none_attacking $rank $i] {
	    set queens($rank) $i
	    if {$rank != 8} {
		x8queens [expr $rank+1]
	    } else {
		solution
		return
	    }
	}
    }
}

proc 8queens {} {
    x8queens 1
}

global interactiveSession
if !$interactiveSession 8queens
Commit	Line	Data
	1	#
	2	# Eight Queens in Tcl
	3	#
	4	# by Karl Lehenbauer, 23 Nov 1990
	5	#
	6	#-----------------------------------------------------------------------------
	7	# $Id: 8queens.tcl,v 2.0 1992/10/16 04:51:36 markd Rel $
	8	#-----------------------------------------------------------------------------
	9	#
	10	proc none_attacking {rank position} {
	11	global queens
	12	loop i 1 $rank {
	13	set j $queens([expr {$rank - $i}])
	14	if {($j==$position-$i) \|\| ($j==$position) \|\| ($j==$position+$i)} {
	15	return 0
	16	}
	17	}
	18	return 1
	19	}
	20
	21	proc solution {} {
	22	global queens
	23	echo $queens(1) $queens(2) $queens(3) $queens(4) $queens(5) $queens(6) $queens(7) $queens(8)
	24	}
	25
	26	proc x8queens {rank} {
	27	global queens
	28	set queens($rank) 1
	29	loop i 1 9 {
	30	if [none_attacking $rank $i] {
	31	set queens($rank) $i
	32	if {$rank != 8} {
	33	x8queens [expr $rank+1]
	34	} else {
	35	solution
	36	return
	37	}
	38	}
	39	}
	40	}
	41
	42	proc 8queens {} {
	43	x8queens 1
	44	}
	45
	46	global interactiveSession
	47	if !$interactiveSession 8queens