python 資料結構--尋找

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1 順序尋找O(n)

def sequential_search(a_list, item):    pos = 0    found = False    while pos < len(a_list) and not found:        if a_list[pos] == item:            found = True        else:            pos = pos+1    return foundtest_list = [1, 2, 32, 8]print sequential_search(test_list, 3)print sequential_search(test_list, 32)

2 二分尋找O(lgn)

def binary_search(a_list, item):    first = 0    last = len(a_list)-1    found = False    while first <= last and not found:        midpoint = (first+last)//2        if a_list[midpoint] == item:            found = True        elif a_list[midpoint] < item:                first = midpoint+1        else:            last = midpoint-1    return foundtest_list = [1, 2, 3, 4, 5, 6]print binary_search(test_list, 3)print binary_search(test_list, 0)

3 雜湊尋找O(1)

概念：來自wikipedia

python 資料結構--尋找