- Added guest contributions by Eric Cheung.

2 files changed, 81 insertions, 104 deletions

diff --git a/challenge-159/eric-cheung/python/ch-1.py b/challenge-159/eric-cheung/python/ch-1.py
index 84e4d54b07..82de733403 100755
--- a/challenge-159/eric-cheung/python/ch-1.py
+++ b/challenge-159/eric-cheung/python/ch-1.py
@@ -1,65 +1,71 @@
 ## Remarks

-## https://www.geeksforgeeks.org/farey-sequence/

+## https://rosettacode.org/wiki/Four_is_magic#Python

 

-## Python3 program to print

-## Farey Sequence of given order

+from collections import OrderedDict

+ 

+numbers = {1: 'one', 2: 'two', 3: 'three', 4: 'four', 5: 'five', 6: 'six', 7: 'seven', 8: 'eight', 9: 'nine'}

 

-## Class for fraction x / y (a term in farey sequence)

-class Term:

+numbers = OrderedDict(sorted(numbers.items(), key = lambda t: t[0], reverse = True))

 

-    ## Constructor to initialize

-    ## x and y in x / y

-    def __init__(self, x, y):

-        self.x = x

-        self.y = y

+def string_representation(i: int) -> str:

+    """

+    Return the english string representation of an integer

+    """

+    if i == 0:

+        return "zero"

 

+    words = ['negative'] if i < 0 else []

 

-## GCD of a and b

-def gcd(a, b):

-    if b == 0:

-        return a

+    working_copy = abs(i)

 

-    return gcd(b, a % b)

+    for key, value in numbers.items():

+        if key <= working_copy:

+            times = int(working_copy / key)

+ 

+            if key >= 100:

+                words.append(string_representation(times))

 

-## Function to print

-## Farey sequence of order n

-def farey(n):

+            words.append(value)

+            working_copy -= times * key

 

-    ## Create a vector to store terms of output

-    v = []

+        if working_copy == 0:

+            break

+ 

+    return " ".join(words)

 

-    ## One by one find and store all terms except 0 / 1 and n / n which are known

-    for i in range(1, n + 1):

-        for j in range(i + 1, n + 1):

 

-            ## Checking whether i and j are in lowest term

-            if gcd(i, j) == 1:

-                v.append(Term(i, j))

+def next_phrase(i: int):

+    """

+    Generate all the phrases

+    """

+    while not i == 4:  # Generate phrases until four is reached

+        str_i = string_representation(i)

+        len_i = len(str_i)

 

-    ## Sorting the term of sequence

-    for i in range(len(v)):

-        for j in range(i + 1, len(v)):

-            if (v[i].x * v[j].y > v[j].x * v[i].y):

-                v[i], v[j] = v[j], v[i]

+        yield str_i, "is", string_representation(len_i)

 

-    ## Explicitly printing first term

-    print("0 / 1", end = " ")

+        i = len_i

+ 

+    ## The Last Phrase

+    yield string_representation(i), "is", "magic"

+ 

+ 

+def magic(i: int) -> str:

+    phrases = []

 

-	## Printing other terms

-    for i in range(len(v)):

-        print("%d/%d" % (v[i].x, v[i].y), end = " ")

+    for phrase in next_phrase(i):

+        phrases.append(" ".join(phrase))

 

-	## explicitly printing last term

-    print("1/1")

+    return f'{", ".join(phrases)}.'.capitalize()

 

 

-# Driver Code

-if __name__ == "__main__":

-    ## n = 5 ## Example 1:

-    ## n = 7 ## Example 2:

-    n = 4 ## Example 3:

+## Driver Code

+ 

+## nInput = 5 ## Example 1:

+## nInput = 7 ## Example 2:

+nInput = 6 ## Example 3:

+    

+strMsg = magic(nInput)

 

-    print("Farey sequence of order %d is" % n)

-    farey(n)

+print (strMsg)

 

-## This code is contributed by sanjeev2552

diff --git a/challenge-159/eric-cheung/python/ch-2.py b/challenge-159/eric-cheung/python/ch-2.py
index 4e19c591df..220bf69b97 100755
--- a/challenge-159/eric-cheung/python/ch-2.py
+++ b/challenge-159/eric-cheung/python/ch-2.py
@@ -1,70 +1,41 @@
 ## Remarks

-## https://www.geeksforgeeks.org/program-mobius-function/

+## https://www.geeksforgeeks.org/equilibrium-index-of-an-array/

 

-## Python program to evaluate

-## Mobius def M(N) = 1 if N = 1

-## M(N) = 0 if any prime factor of N is contained twice

-## M(N) = (-1) ^ (no of distinct prime factors)

+## Python Program to Find Equilibrium Index of an Array

 

+## Function to Find the Equilibrium Index

+def equilibrium(arr):

+    leftsum = 0

+    rightsum = 0

 

-import math

+    n = len(arr)

 

+	## Check for Indexes one by one until an equilibrium index is found

+    for i in range(n):

+        leftsum = 0

+        rightsum = 0

 

-## def to check if n is prime or not

-def isPrime(n) :

+		## Get Left Sum

+        for j in range(i):

+            leftsum = leftsum + arr[j]

 

-    if (n < 2) :

-        return False

+		## Get Right Sum

+        for j in range(i + 1, n):

+            rightsum = rightsum + arr[j]

 

-    for i in range(2, n + 1) :

-        if (n % i == 0) :

-            return False

- 

-        i = i * i

- 

-    return True

-

-

-def mobius(n) :

-

-    p = 0

-

-	## Handling 2 separately

-    if (n % 2 == 0) :

-

-        n = int(n / 2)

-        p = p + 1

-

-        ## If 2^2 also divides N

-        if (n % 2 == 0) :

-            return 0

-

-    ## Check for all other prime factors

-    for i in range(3, int(math.sqrt(n)) + 1) :

-

-        ## If i divides n

-        if (n % i == 0) :

-

-            n = int(n / i)

-            p = p + 1

-

-            ## If i ^ 2 also divides N

-            if (n % i == 0) :

-                return 0

-

-        i = i + 2

-

-    if(p % 2 == 0) :

-        return -1

-

-    return 1

+		## If Left Sum and Right Sum are same, then we are done

+        if leftsum == rightsum:

+            return i

+	

+	## return -1 if no equilibrium index is found

+    return -1

+			

 

 ## Driver Code

-## N = 5 ## Example: 1

-## N = 10 ## Example: 2

-N = 20 ## Example: 3

+arr = [1, 3, 5, 7, 9] ## Example 1:

+## arr = [1, 2, 3, 4, 5] ## Example 2:

+## arr = [2, 4, 2] ## Example 3:

 

-print ("Mobius defs M(N) at N = {} is: {}\n" . format(N, mobius(N)));

+print (equilibrium(arr))

 

-							

-## This code is contributed by Manish Shaw (manishshaw1)

+## This code is contributed by Abhishek Sharama