[punch in - Blue Bridge Cup] day 3 --- slice in reverse order list[: -1]

subject 1 ： Based on practice Yanghui triangle

Their thinking

” The first i+1 Line is (a+b)i The coefficients of the expansion of “, therefore Use $C_i^k$ Calculation
Method 2 ： Two dimensional array

Code

def factorial(n):
    """  Calculate the factorial  :param n: The number to be calculated  :return:  result  """
    f = 1
    for i in range(1, n+1):
        f = f * i
    return f

def cik(n, k):
    """  Calculate the number of combinations  :param n: Count down  :param k: Upper number  :return: Combination number result  """
    return int(factorial(n) / (factorial(k) * factorial(n-k)))

n = int(input())
for i in range(1, n+1):
    for j in range(1, i+1):
        print(cik(i-1, j-1), end=' ')
    print()

#  Method 2 
n = int(input())
num = [[0 for j in range(n)] for i in range(n)]
num[0][0] = 1
print(1)
for i in range(1, n):
    num[i][0] = 1
    print(1, end=' ')
    for j in range(1, i+1):
        num[i][j] = num[i-1][j-1] + num[i-1][j]
        print(num[i][j], end=' ')
    print()

subject 2 Based on practice Special numbers

Their thinking

Judge

Code

def is_ans(n):
    a = n % 10
    b = (n // 10) % 10
    c = (n // 100) % 10
    if n == pow(a, 3) + pow(b, 3) + pow(c, 3):
        print(n)
for i in range(100, 1000):
    is_ans(i)

subject 3 ： Based on practice Palindrome number

Their thinking

python section , Positive and negative order are equal

Code

for i in range(1000, 10000):
    if i == int(str(i)[::-1]):
        print(i)

subject 4 ： Based on practice Special palindrome number

Their thinking

python section , Positive and negative order are equal
Run timeout , Because every time the judgment is calculated , Later method After judging that it is not palindrome number , Do not perform subsequent judgments

Code

"""  Run timeout , Because every time the judgment is calculated , Later method   After judging that it is not palindrome number , Do not perform subsequent judgments  n = int(input()) for i in range(10000, 1000000): iStr = str(i) sum = 0 for j in range(len(iStr)): sum += int(iStr[j]) if iStr == iStr[::-1] and sum == n: print(i) """
def is_pal(num):
    num = str(num)
    if num == num[::-1]:
        return True
    else:
        return False
def sum_num(num):
    sum = 0
    num = str(num)
    for i in range(len(num)):
        sum += int(num[i])
    return sum

n = int(input())
for num in range(10000, 1000000):
    if is_pal(num) and sum_num(num) == n:
        print(num)