1 files changed, 47 insertions, 0 deletions
diff --git a/challenge-221/eric-cheung/python/ch-2.py b/challenge-221/eric-cheung/python/ch-2.py
new file mode 100755
index 0000000000..0288a402e5
--- /dev/null
+++ b/challenge-221/eric-cheung/python/ch-2.py
@@ -0,0 +1,47 @@
+
+## Remarks
+## https://www.geeksforgeeks.org/generating-all-possible-subsequences-using-recursion/
+
+## Python3 code to print all possible subsequences for given array using recursion
+## Recursive function to print all possible subsequences for given array
+
+nMaxArrLen = 0
+
+def IsArithmetic (arrListCheck):
+
+    nDiff = arrListCheck[1] - arrListCheck[0]
+    for nIndxLoop in range(2, len(arrListCheck)):
+        if arrListCheck[nIndxLoop] - arrListCheck[nIndxLoop - 1] != nDiff:
+            return False
+
+    return True
+
+def GenSubseqArr (arrFunc, nIndx, subArrFunc):
+
+    global nMaxArrLen
+
+    ## Print the subsequence when reach the leaf of recursion tree
+    if nIndx == len(arrFunc):
+        ## Condition to avoid printing empty subsequence
+        ## if len(subArrFunc) > 0:
+        if len(subArrFunc) > 2 and IsArithmetic(subArrFunc):
+            ## print (subArrFunc)
+            if len(subArrFunc) > nMaxArrLen:
+                nMaxArrLen = len(subArrFunc)
+
+    else:
+        ## Subsequence without including the element at current nIndx
+        GenSubseqArr(arrFunc, nIndx + 1, subArrFunc)
+
+        ## Subsequence including the element at current nIndx
+        GenSubseqArr(arrFunc, nIndx + 1, subArrFunc + [arrFunc[nIndx]])
+
+    return
+
+arrGivenMain = [9, 4, 7, 2, 10]  ## Example 1
+## arrGivenMain = [3, 6, 9, 12]  ## Example 2
+## arrGivenMain = [20, 1, 15, 3, 10, 5, 8]  ## Example 3
+
+GenSubseqArr(arrGivenMain, 0, [])
+
+print (nMaxArrLen)