more recursion

AIML/Numpy/Numpy.py

@@ -72,7 +72,7 @@
     print()
 
     print("random matrix of size, standard random variable")
-    e=np.random.rand(4)
+    e=np.random.randn(4)
     print(e)
     print()
 

DSA/recursion/String.py

@@ -0,0 +1,20 @@
+def reverse(s):
+    if not s:
+        return ""
+    return reverse(s[1:])+s[0]
+
+def count_specific_char_in_string(s,_char):
+    if not s:
+        return 0
+    if s[0]==_char:
+        return 1 + count_specific_char_in_string(s[1:],_char)
+    else:
+        return count_specific_char_in_string(s[1:],_char)
+
+
+if __name__ == '__main__':
+    print(f"!NataSha = {reverse('!NataSha')}")
+
+    str = "axbxcx"
+    c = "x"
+    print(f"{c} in {str} is repeated {count_specific_char_in_string(str,c)} times")

DSA/recursion/SumOfNumbers.py

@@ -0,0 +1,15 @@
+def sum_of_numbers(array):
+    if not array:
+        return 0
+    # this statement is not needed because , a[1:] on an array with one value will give empty array
+    #if(len(array))==1:
+        #return array[0]
+    return array[0]+sum(array[1:])
+
+
+if __name__ == '__main__':
+    arr = [1,2,3,4]
+    print(f"sum of {arr} is {sum_of_numbers(arr)}")
+
+    arr = [10,20,3,14]
+    print(f"sum of {arr} is {sum_of_numbers(arr)}")