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.
水仙花数是从左向右和从右向左读都相同的自然数。求两个三位数的乘积中最大的水仙花数。
def problem4(): min, max = 100, 999 def isPalindromic(num): if num<=10: return False digits = list(str(num)) revdigs = list(str(num)) revdigs.reverse() return digits==revdigs x = y = avg = max while avg>=min: num = x*y if isPalindromic(num): return x,y,num elif x<=min or y>=max: avg -= 0.5 x = int(avg) y = int(avg+0.5) else: x -= 1 y += 1 if __name__=='__main__': print str(problem4())
考虑两个三位数乘积最大的是 999x999, (平均数999)
其次是 998x999, (平均数998.5)
再次是 998x998, 997x999, (平均数998)
然后是 997x998, 996x999, (平均数997.5)
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