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38 lines
863 B
Python
38 lines
863 B
Python
arr = [ int(x) for x in open('input').read().split(',') ]
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idx = 30000000
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def lookback(n, arr):
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arr.reverse()
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A = 0; c = 0
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for x in arr:
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c += 1
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if x == n:
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if A == 0:
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A = c
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else:
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return c - A
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return 0
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def a(arr, idx):
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for t in range(len(arr),idx):
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arr.append(lookback(arr[t-1], arr[:t]))
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return arr[idx-1]
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# print(a(arr, idx))
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# OK the lookback approach is slow AF. Let's try arr different method!
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def lut_search(lut, n, idx):
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if n in lut:
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d = idx - lut[n]
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lut[n] = idx
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return d
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else:
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lut.update({ n: idx })
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return 0
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def b(arr, idx):
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lut = { arr[x]:x+1 for x in range(len(arr)) }
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for t in range(len(arr),idx):
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arr.append(lut_search(lut, arr[t-1], t))
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return arr[idx-1]
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print(b(arr, idx)) |