142 lines
3.2 KiB
Tcl
Executable File
142 lines
3.2 KiB
Tcl
Executable File
#!/usr/bin/env tclsh
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source ../prelude.tcl
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proc read-input {input} {
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global grid
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global width
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global height
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set i 0
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while {[gets $input line] >= 0} {
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set j 0
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foreach c [split $line ""] {
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set grid($i,$j) $c
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incr j
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}
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incr i
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}
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set height $i
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set width $j
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}
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proc reset-visited {} {
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global visit
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set visit [dict create]
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}
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proc mark-visited {x y d} {
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global visit
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set v [switch -exact -- $d n {expr 1} s {expr 2} w {expr 4} e {expr 8} default {error "invalid dir '$d'"}]
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dict incr visit $y,$x 0
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set old [dict get $visit $y,$x]
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dict set visit $y,$x [expr {$old | $v}]
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return [expr {($old & $v) != 0}]
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}
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proc print-visited {} {
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global visit
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global width
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global height
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for {set i 0} {$i < $height} {incr i} {
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set row {}
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for {set j 0} {$j < $width} {incr j} {
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if {[dict exists $visit $i,$j] && [dict get $visit $i,$j]} {
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lappend row "#"
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} else {
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lappend row "."
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}
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}
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puts [join $row ""]
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}
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}
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proc follow {beams {first 0}} {
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global grid
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set newbeams {}
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foreach {x y d} $beams {
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if {!$first} {
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if { [mark-visited $x $y $d] } continue
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switch $d {
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n { incr y -1 }
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s { incr y +1 }
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w { incr x -1 }
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e { incr x +1 }
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}
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}
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if {[info exists grid($y,$x)]} {
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switch -exact "$grid($y,$x) $d" {
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{\ n} { set d w }
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{\ s} { set d e }
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{\ e} { set d s }
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{\ w} { set d n }
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{/ n} { set d e }
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{/ s} { set d w }
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{/ e} { set d n }
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{/ w} { set d s }
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{| w} { set d {n s} }
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{| e} { set d {n s} }
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{- n} { set d {w e} }
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{- s} { set d {w e} }
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}
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foreach d' [split $d] {
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lappend newbeams $x $y ${d'}
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}
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}
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}
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return $newbeams
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}
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proc solve {} {
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global visit
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reset-visited
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set beams [follow {0 0 e} 1]
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while {[llen $beams] > 0} {
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set beams [follow $beams]
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}
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print-visited
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puts [dict size $visit]
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}
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proc lmax {list} {
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set t 0
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foreach x $list { if {$t < $x} {set t $x} }
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return $t
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}
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proc solve2 {} {
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global grid
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global width
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global height
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global visit
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puts "width=$width height=$height"
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set edges {}
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foreach k [array names grid] {
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lassign [split $k ","] y x
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if {$x == 0} { lappend edges [list $x $y e] }
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if {$y == 0} { lappend edges [list $x $y s] }
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if {$x == $width - 1} { lappend edges [list $x $y n] }
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if {$y == $height - 1} { lappend edges [list $x $y w] }
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}
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set l {}
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foreach beams $edges {
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reset-visited
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set beams [follow $beams 1]
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while {[llen $beams] > 0} {
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set beams [follow $beams]
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}
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puts [dict size $visit]
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lappend l [dict size $visit]
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}
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puts [lmax $l]
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}
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read-input stdin
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puts [array get grid]
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puts [follow {0 0 e}]
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puts [dict get $visit]
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solve
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solve2
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