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我已經使用Sedgewick在課程中教授的算法,在Python中編寫了Mergesort的實現。我無法正確分類。代碼有什麼問題?無法編寫合併代碼
def merge(a, aux, lo, mid, hi):
assert isSorted(a, lo, mid)
assert isSorted(a, mid+1, hi)
for k in range(lo, hi):
aux[k] = a[k]
i = lo
j = mid + 1
for k in range(lo, hi):
if i > mid:
a[k] = aux[j]
j += 1
elif j > hi:
a[k] = aux[i]
i += 1
elif a[i] < a[j]:
a[k] = aux[i]
i += 1
else:
a[k] = aux[j]
j += 1
assert isSorted(a, lo, hi)
def sort(a, aux, lo, hi):
if (lo >= hi): return a
mid = math.floor(lo + (hi-lo)/2)
sort(a, aux, lo, mid)
sort(a, aux, mid+1, hi)
merge(a, aux, lo, mid, hi)
def merge_sort(a):
aux = [0] * len(a)
sort(a, aux, 0, len(a))
assert isSortedArray(a)
也許你試着調試? – Herokiller 2014-10-31 03:23:37