kokozeng / datastructure Goto Github PK

def fab(max): 
    n, a, b = 0, 0, 1 
    while n < max: 
        yield b      # 使用 yield
        #print (b) 
        a, b = b, a + b 
        n = n + 1
for n in fab(6):
    print (n, end = ' ')

# 递归方式
def binary_search(alist, first, last, item):
    mid = (first + last)//2
    # 递归的退出条件
    if alist[mid] == item :
        print(mid)
        return mid
    if alist[mid] > item:
        binary_search(alist, first, mid - 1, item)
    else:
        binary_search(alist, mid + 1, last, item)

if __name__ == "__main__":
    alist=[12,34,56,45,23,523,64,123,5346,4,30]
    # 因为查找是针对有序的顺序表
    alist.sort()
    print(alist)
    pos = binary_search(alist, 0, len(alist)-1, 123)
    # 为什么输出是none return出问题了吗？
    print(pos)

# 快速排序
def quick_sort(alist, first, last):
    if first >= last:
        return
    min_value = alist[first]
    low = first
    high = last

    while high > low:
        while low < high and alist[high] >= min_value:
            high -= 1
        alist[low] = alist[high]
        while low < high and alist[low] < min_value:
            low +=1
        alist[high] = alist[low]
    alist[low] = min_value
    
    quick_sort(alist, first, low-1)
    quick_sort(alist, low+1, last)
    
if __name__ == "__main__":
    alist=[12,34,56,45,23,523,64,123,5346,4,30]
    quick_sort(alist, 0, len(alist)-1)
    print(alist)

alist = quick_sort(alist, 0, len(alist)-1)

s='abc00000 12345678 90000000'
s = s.split()
print("将字符串按空格分割:", s)
s.sort()
print("字符串升序:", s)
s.sort(reverse=True)
print("字符串降序:", s)


# 获取列表的第二个元素
def takeSecond(elem):
    return elem[0]
 
# 指定第二个元素排序
'''没看懂这里是什么操作, 不是takeSecond(s)吗？还有这个key在排什么序也不懂'''
s.sort(key=takeSecond)
 
# 输出类别
print ('排序列表：', s)