79 lines
1.7 KiB
Python
79 lines
1.7 KiB
Python
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# Write a function with the following type signature:L
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# equal? :: String -> String -> Bool
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#
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# Determine equality between two inputs with backspace characters encoded as
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# "<".
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################################################################################
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# Solution 1
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################################################################################
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# from collections import deque
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# def equal(a, b):
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# sa = deque()
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# sb = deque()
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# for c in a:
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# if c == '<':
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# sa.pop()
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# else:
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# sa.append(c)
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# for c in b:
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# if c == '<':
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# sb.pop()
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# else:
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# sb.append(c)
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# return sa == sb
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################################################################################
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# Solution 2
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################################################################################
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def handle_dels(num_dels, i, xs):
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if i < 0:
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return -1
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while xs[i] == '<':
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num_dels += 1
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i -= 1
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while num_dels > 0 and xs[i] != '<':
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num_dels -= 1
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i -= 1
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if xs[i] == '<':
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return handle_dels(num_dels, i, xs)
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else:
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return i
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def update_index(i, xs):
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# TODO: Indexing into non-available parts of a string.
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if xs[i] != '<' and xs[i - 1] != '<':
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return i - 1
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elif xs[i - 1] == '<':
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return handle_dels(0, i - 1, xs)
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def equal(a, b):
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ia = len(a) - 1
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ib = len(b) - 1
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while ia >= 0 and ib >= 0:
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if a[ia] != b[ib]:
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return False
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ia = update_index(ia, a)
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ib = update_index(ib, b)
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if ia != 0:
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return update_index(ia, a) <= -1
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if ib != 0:
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return update_index(ib, b) <= -1
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return True
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