#;2> (topological-sort
'((i am)
(not trying)
(confuse the)
(am trying)
(trying to)
(am not)
(trying the)
(to confuse)
(the issue))
eqv?)
(not i am trying to confuse the issue)以这种方式对子列表进行排序可能会使正确的输出更加清晰:
(i am)
(am not)
(not trying)
(trying to)
(to confuse)
(am trying)
(confuse the)
(trying the)
(the issue)看起来这个命令应该是:
i am not trying to confuse the issue这是一个bug,还是我漏掉了什么?
--编辑:
将子列表与公共头部相结合:
(topological-sort
'((i am)
(not trying)
(confuse the)
(am trying not)
(trying to the)
(to confuse)
(the issue))
eqv?)
(i am not trying to confuse the issue)因此,似乎正确的方法是对输入进行预处理,以确保没有两个子列表共享相同的头。
解决Rosetta Code拓扑排序问题:
(use srfi-1) ; list operators
(use srfi-69) ; hash-tables
(define data
'((des_system_lib std synopsys std_cell_lib des_system_lib dw02 dw01 ramlib ieee)
(dw01 ieee dw01 dware gtech)
(dw02 ieee dw02 dware)
(dw03 std synopsys dware dw03 dw02 dw01 ieee gtech)
(dw04 dw04 ieee dw01 dware gtech)
(dw05 dw05 ieee dware)
(dw06 dw06 ieee dware)
(dw07 ieee dware)
(dware ieee dware)
(gtech ieee gtech)
(ramlib std ieee)
(std_cell_lib ieee std_cell_lib)
(synopsys)))
(define table (make-hash-table))
(for-each
(lambda (xs)
(let ((head (car xs)) (tail (cdr xs)))
(for-each
(lambda(key)
(when (not (eqv? key head))
(hash-table-update!/default
table key (lambda (accum) (cons head accum)) '())))
tail)))
data)
(define answer
(topological-sort (hash-table->alist table) eqv?))
answer一个可能的结果(因为哈希表是无序的,所以每次都可能是不同的):
(std ieee dware dw05 dw06 dw07 ramlib std_cell_lib gtech synopsys
dw02 dw01 des_system_lib dw03 dw04)正在尝试验证答案:
(any
(lambda (tail)
(any
(lambda (key)
(and (hash-table-exists? table key)
(member (car tail) (hash-table-ref table key))))
(cdr tail)))
(reverse (pair-fold cons '() answer)))
#f这似乎是正确的。
https://stackoverflow.com/questions/44578335
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