gulan

module CombinatorialHierarchy where

{- https://en.wikipedia.org/wiki/Combinatorial_hierarchy

3, 2^3-1, 2^7-1, 2^127-1

seq:
    3, 7,     127,   170141183460469231731687303715884105727

cumulative sum:

gulan

#!/usr/bin/env python

# The way I usually write it.
"""
rep customers:
    seq onecust:
        invest
        alt movement:
            payin
            withdraw

gulan

#!/usr/bin/env python

data = """a 9
b 2
c 2
d 4
e 12
f 2
g 3
h 2

gulan

/* Exercise 1-13. Write a program to print a histogram of the lengths
of words in its input. */

/*
  input = (special | word)*
  special = blank | tab | newline
  word = non-special+
 */

#include<stdio.h>

gulan

/* Count words, lines and characters.*/

/*
  The number of lines is just the number of newline chars. Every
  character, including newline is counter as a character. EOF is not a
  character.

  I use a structure design rather than an IN/OUT state flag.
  
  A sequence of chars not including blank, tab or newline is a

gulan

#include<assert.h>
#include<stdio.h>

/* htoi(): convert hext digit string to native int. */

/*
left-to-right recursive:
htoir("2") == 2
htoir("A") == 10
htoir("23") == 16*htoir("2") + 3

gulan

/*
Display the length of the the longest line from text input.
 */

/*
[Skip the write-up as I did not follow it when writing the code.]

A simple text file is an iteration of lines, followed by EOF.

    simple = body + EOF

gulan

#include<assert.h>
#include<stdio.h>
#include<string.h>

/* The function squeeze removes all instances of specified characters
from the input string array. The characters to be excluded are given in
a second argument.*/

struct testrec {
  char inpu[30];

gulan

#!usr/bin/env python

from __future__ import print_function

"""
A tree is a restricted graph. Both trees and graphs may represented as
a set of (parent, child) pairs.
"""

t = set([(1,2), (1,3), (1,7), (2,4), (2,5), (4,6), (7,8), (7,9)])

gulan

import types

# - - - - - countdown - - - - -

def countdown(n):
    # Tail recursive call will overflow Python's stack for large n.
    return n if n == 0 else countdown(n-1)

assert countdown(5) == 0