Question

所以我的代码出于某种原因给了我错误：

TypeError: Can't convert 'int' object to str implicitly

这与线路有关：

answer = answer + combination(row, column) + "\t"

这是我的代码：

def combination(n, k):
    if k == 0 or k == n:
        return 1
    return combination(n - 1, k - 1) + combination(n - 1, k)

def pascals_triangle(rows):
    for row in range(rows):
        answer = ""
        for column in range(row + 1):
            answer = answer + combination(row, column) + "\t"
        print(answer)

pascals_triangle(10)

Answer 1

TypeError：无法转换＆＃39; int＆＃39;隐含地反对str

在这一行：

answer = answer + combination(row, column) + "\t"
         ^        ^                           
         |__ str  |__ int

combination()会返回int，而在Python中则无法执行＆＃34; str + int＆＃34;隐式地，所以明确地将它转换为str：

answer = answer + str(combination(row, column)) + "\t"

您还可以避免使用字符串连接：

answer = '{ans} {comb} \t'.format(ans=answer, comb=combination(row, column))

Answer 2

独立于修复您当前问题的str()转换问题，我想触及您的计算Pascal三角形的算法。您的方法独立地计算每一行，忽略计算的上一行为您提供了下一行的步骤。考虑我的（非递归）方法：

def pascals_triangle(rows):
    array = []

    for row in range(rows):
        array.append(1)  # both widens the row and initializes the last element

        for i in range(row - 1, 0, -1):  # fill in the row, right to left
            array[i] += array[i - 1]  # current computed from previous

        print(*array, sep="\t")

在我的系统上将行数从10增加到25，这种方法的速度提高了约400倍。这是由于算法，而不是递归。同样的方法可以递归和快速完成：

def pascals_triangle(rows):
    array = [1]

    if rows > 1:
        array[0:0] = pascals_triangle(rows - 1)

        for i in range(rows - 2, 0, -1):  # fill in the row, right to left
            array[i] += array[i - 1]  # current computed from previous

    print(*array, sep="\t")
    return array  # return the last completed row

Pascal的三角形 - 类型错误

2 个答案: