Blue Bridge Cup - palindromes and special palindromes

Topic 1

Subject requirements

 Resource constraints 
 The time limit ：1.0s    Memory limit ：512.0MB
 Problem description 
	1221 It's a very special number , It's the same thing to read from the left as it is to read from the right , Programming for all such four decimal numbers .
 Output format 
	 According to the order from small to large output to meet the conditions of four decimal numbers .

Solution 1 ：

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

Solution 2 ：

Through the symmetry of palindrome number , We can simplify the original four digits to two digits , In order to reduce CPU And memory usage

l = []
for i in range(10,100):
	l.append(str(i) + str(i)[::-1])
for i in sorted(map(int,l)):
	print(i)

Topic two

Subject requirements

 Resource constraints 
 The time limit ：1.0s    Memory limit ：512.0MB
 Problem description 
　　123321 It's a very special number , It's the same thing to read from the left as it is to read from the right .
　　 Enter a positive integer n,  Programming for all such five and six decimal numbers , The sum of your numbers equals n .
 Input format 
　　 The input line , Contains a positive integer n.
 Output format 
　　 Output the integers satisfying the conditions in the order of small to large , Each integer takes up one line .
 The sample input 
52
 Sample output 
899998
989989
998899
 Data size and engagement 
　　1<=n<=54.

Solution 1 ：

Ideas ： First, traverse all five and six digits , Determine whether it conforms to the basic characteristics of palindrome number through slice inversion list . If it conforms to , Judge whether the numbers and answers of this question meet the special requirements , Output if yes .

n = int(input())
for i in range(10000,1000000):
	a = str(i)
	if a == a[::-1]:
		if n == sum(int(j) for j in a):
			print(a)

Solution 2 ：

Solution 2 of the same principle , That is, through the symmetry of palindromes , Simplify the original five or six digits to three digits , Similarly, the slice inversion method is used to judge whether the five digit and six digit meet the conditions .

n = int(input())
l = []
for i in range(100,1000):
	if sum(map(int,str(i)+(str(i)[:2])[::-1])) == n: # Five figures 
		l.append(str(i)+(str(i)[:2])[::-1])
	if sum(map(int,str(i)+str(i)[::-1])) == n:       # Six figures 
		l.append(str(i)+str(i)[::-1])
for i in sorted(map(int,l)): # Output the integers satisfying the conditions in the order of small to large 
	print(i)

By running the code of solution one and solution two , Discovery solution I CPU The usage is 390ms, And solution two has only 31ms.