Day20:给定两个字符串，求两数之和
eg : inpur: num1 = "12",num2 = "23"
output : 35
#不能直接将字符串转换成整数进行相加
1 def add_num(num1,num2): 2 res = "" #用来存储每位的数字 3 i = len(num1) - 1 #num1的尾部 4 j = len(num2) - 1 #num2的尾部 5 carry = 0 #看是否产生进位，初始不进位，所以为0 6 while i >= 0 or j >= 0: 7 n1 = int(num1[i]) if i >= 0 else 0 8 n2 = int(num2[j]) if j >= 0 else 0 9 tmp = n1 + n2 + carry 10 carry = tmp // 10 11 res = str(tmp % 10) + res 12 i -= 1 13 j -= 1 14 return '1' + res if carry else res 15 16 17 num1 = '12' 18 num2 = '23' 19 print(add_num(num1,num2))
输出结果：35
另一种情形：给定一个列表和一个数字，求出他们的和
eg : input : A = [9,9,9,9,9,9,9,9,9,9] ,K = 1
output : 10000000000
1 def addTOArrayForm(A,k): 2 res = "" 3 i = len(A) - 1 4 j = len(str(k)) - 1 5 carry = 0 6 while i >= 0 or j >= 0: 7 n1 = A[i] if i >= 0 else 0 8 n2 = int(str(k)[j]) if j >= 0 else 0 9 tmp = n1 + n2 + carry 10 carry = tmp // 10 11 res = str(tmp % 10) + res 12 i -= 1 13 j -= 1 14 15 return '1' + res if carry else res 16 17 A = [9,9,9,9,9,9,9,9,9,9] 18 K = 1 19 print(addTOArrayForm(A,K))
输出结果：