Project Euler Problem4

Largest palindrome product

Problem 4

A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 99.

Find the largest palindrome made from the product of two 3-digit numbers.

 

The python code is as follows:

def isPalindromic(data):
    list = []
    while data > 10:
        list.append(data%10)
        data = int(data/10)
    list.append(data)
    print(list)
    i = 0
    j = len(list)-1
    while i < j:
        if list[i] != list[j]:
            return False
        i += 1
        j -= 1
    return True
    
a = 999
total = 0
result = 0
targetA = 0
targetB = 0
while a >= 100:
    b = 999
    if a*b < result:
        break
    while b >= 100:
        total = a*b
        if total < result:
            break
        if isPalindromic(total):
            result = total
            targetA = a
            targetB = b
        b -= 1
    a -= 1
    
print(result)
print(targetA)
print(targetB)

　　Assuming b is large than a, we can rewrite the code like this:

def isPalindromic(data):
    list = []
    while data > 10:
        list.append(data%10)
        data = int(data/10)
    list.append(data)
    print(list)
    i = 0
    j = len(list)-1
    while i < j:
        if list[i] != list[j]:
            return False
        i += 1
        j -= 1
    return True
    
a = 999
total = 0
result = 0
targetA = 0
targetB = 0
while a >= 100:
    b = 999
    if a*b < result:
        break
    while b >= a:
        total = a*b
        if total < result:
            break
        if isPalindromic(total):
            result = total
            targetA = a
            targetB = b
        b -= 1
    a -= 1
    
print(result)
print(targetA)
print(targetB)