算法课笔记(1)-递归实现全排列与整数的划分

递归实现全排列

def arrange(lst, start, end):
    if start == end:
        print(lst)
    else:
        for i in range(start, end+1):
            lst[start], lst[i] = lst[i], lst[start]
            arrange(lst, start+1, end)
            lst[start], lst[i] = lst[i], lst[start]
lst = list("abc")
arrange(lst, 0, 2)

整数的划分

def divide(n, m):
    if n == 1 or m == 1:
        return 1
    elif n < m:
        return divide(n, n)
    elif n == m:
        return 1+divide(n, m-1)
    elif n > m and m > 1:
        return divide(n, m-1) + divide(n-m, m)
print(divide(6, 6))