champernowne.py

Created on February 16, 2020

272 Bytes

Calcule la n-ième décimale du nombre de Champernowne (0,123456789101112131415…) avec deux fonctions. brutale ne permet pas d’aller trop loin, maline est plus rapide et plus économe.

def champer(n):
  return ((9*n-1)*10**n+1)//9

def brutale(n):
  s=""
  i=1
  while len(s)<n:
    s+=str(i)
    i+=1
  return s[n-1]

def maline(n):
  i=0
  while champer(i)<n:
    i+=1
  i-=1
  q,r=divmod(n-champer(i)-1,i+1)
  return str(q+10**(i))[r]

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