done with q1,q2,q3

Q1/solution.py

@@ -1 +1,24 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+"""
+Created on Mon Sep 26 21:33:58 2022
+
+@author: sahab
+"""
+
 ## Add code below with answer clearly stated
+
+def factorial(n):
+    if n <= 1:
+        return 1
+    else:
+        return n * factorial(n-1)
+
+def sum_of_digit(n):
+    return 0 if n == 0 else int(n % 10) + sum_of_digit(int(n / 10)) 
+
+x = sum_of_digit(factorial(10))
+assert x == 27
+
+x = sum_of_digit(factorial(100))
+assert x == 675

Q2/solution.py

@@ -5,4 +5,18 @@
 #         self.next = next
 class Solution:
     def removeNthFromEnd(self, head: Optional[ListNode], n: int) -> Optional[ListNode]:
-
+        if self.head is None:
+            return
+        index = 0
+        current = self.head
+
+        while current.next and index < n:
+            previous = current
+            current = current.next
+            index += 1
+
+        if index == 0:
+            self.head = self.head.next
+        else:
+            previous.next = current.next
+

Q3/solution.py

@@ -1,3 +1,25 @@
 class Solution:
     def findMedianSortedArrays(self, nums1: List[int], nums2: List[int]) -> float:
+        le1, le2 = len(nums1), len(nums2)
+        total = le1 + le2 
+        half = total // 2
+        if le1 < le2:
+            return self.findMedianSortedArrays(nums2, nums1)
+        l, r = 0, len(nums1) - 1
+        while True:
+            i = (l + r) // 2
+            j = half - i - 2
+
+            aleft = nums1[i]
+            aright = nums1[i+1]
+            bleft = nums1[j]
+            bright = nums1[j+1]
 
+            if aleft <= bright and bleft <= aright:
+                if total % 2 == 0:
+                    return min(aright, bright)
+                return (max(aleft, bleft) + min(aright, bright)) / 2
+            elif aleft > bright:
+                r = i - 1
+            else:
+                l = i + 1