new ques

Author: harishpuvvada

Lists/Circular_counter.py

@@ -12,11 +12,11 @@
 a = ['1','2','3','4','5','6','7','8','9']
 
 def harish(int_list, skip):
-  skip = skip - 1 #we are doing this because list starts with 0 index
-  idx = 0
-  while len(int_list)>0:
-    idx = (skip+idx)%len(int_list) #hashing to keep changing the index to every 3rd, idx should be smaller than len(list)-so using %
-    print(int_list.pop(idx))
+    skip = skip - 1 #we are doing this because list starts with 0 index
+    idx = 0
+    while len(int_list)>0:
+        idx = (skip+idx)%len(int_list) #hashing to keep changing the index to every 3rd, idx should be smaller than len(list)-so using %
+        print(int_list.pop(idx))
 
 harish(a,3)
 

Lists/LeastIntegerNotInAList.py

@@ -6,13 +6,15 @@
 import  itertools
 sum_list = []
 GivenArr = [1, 2, 5, 7]
+
 for L in range(0, len(GivenArr)+1): #for lengths of 0,1,2,3,4
     for subset in itertools.combinations(GivenArr, L): #find different subsets for each length in above line
         sum_list.append(sum(subset)) #write all the sums in to this newlist
 
 new_list = list(set(sum_list)) #finding unique sums
 new_list.sort()
 print(new_list)
+
 for each in range(0,new_list[-1]+2): #cuz if all possible sums are already possible, then "highest+1" is our ans
     if each not in new_list:
         print(each)

Lists/List - allPermutationsToAGivenSum.py

@@ -1,15 +1,20 @@
+"""Given a list of integers and a target, print subset of list which add up to target.
+Note: Can be more than one subset """
+
+
+
 def subset_sum(numbers, target, partial=[]):
-    print(partial)
+    #print(partial)
     s = sum(partial)
 
     if(s == target):
         print("sum of ",partial,"=",target)
 
-    if s>= target:
+    if s >= target:
         return
 
     for i in range(len(numbers)):
-        print("iteration",i)
+        #print("iteration",i)
         n = numbers[i]
         rest = numbers[i+1:]
         subset_sum(rest,target,partial + [n])

Lists/Queue-UsingTwoStacks.py

@@ -10,23 +10,20 @@
 class Queue2Stacks(object):
 
     def __init__(self):
-        # Two Stacks
-        self.in_stack = []
+        
+        self.in_stack = []          # Two Stacks
         self.out_stack = []
 
-    def enqueue(self, element):
 
+    def enqueue(self, element):
         self.in_stack.append(element)
-        pass
 
-    def dequeue(self):
 
+    def dequeue(self):
         if not self.out_stack:
             while self.in_stack:
                 self.out_stack.append(self.in_stack.pop())
         return self.out_stack.pop()
-        pass
-
 
 
 q = Queue2Stacks()

Lists/Queues.py

@@ -1,16 +1,12 @@
-"""Make a Queue class using a list!
-Hint: You can use any Python list method
-you'd like! Try to write each one in as
-few lines as possible.
-Make sure you pass the test cases too!"""
+"""Make a Queue class using a list!"""
 
 
 class Queue:
     def __init__(self, head=None):
         self.storage = [head]
 
     def enqueue(self, new_element):
-    	self.storage.append(new_element).  #append generally appends at the tail
+    	self.storage.append(new_element)  #append generally appends at the tail
 
     def peek(self):
     	return self.storage[0]   # element at head . so storage[0]

Lists/SummaryOfRanges.py

@@ -7,10 +7,12 @@
 
 def summaryRanges(arr):
     summary = []
+    
     if len(arr) == 1:         # base condition
         return [str(arr[0])]
 
     i = 0
+
     while (i < len(arr)):
         temp = ""
         start = str(arr[i])

Lists/Top K Frequent elements.py

@@ -15,5 +15,5 @@ def topKFrequent(self, nums, k):
         :type k: int
         :rtype: List[int]
         """
-        c = collections.Counter(nums)
-        return [x[0] for x in c.most_common(k)] #Here x is a tuple. only tuples can form keys not lists.
+        c = collections.Counter(nums) #returns a dict with {num : how many times this num appeared in the list}
+        return [x[0] for x in c.most_common(k)] # Here x is a tuple. only tuples can form keys not lists.

Lists/allSubsetsOfASet.py

@@ -2,15 +2,15 @@
 total = len(numbers)
 
 def subset_sum(numbers, partial=[]):
-    global total
+    global total         # this is how you use global variables inside a function in python
+ 
+    if(len(partial)>= total): # base case - when to stop recursion
+        return
 
-    if (len(partial)<= total):
+    if (len(partial)<= total): 
         print(partial)
 
-    if(len(partial)>= total):
-        return
-
-    for i in range(len(numbers)):
+    for i in range(len(numbers)): 
         n = numbers[i]
         rest = numbers[i+1:]
         subset_sum(rest,partial + [n])

Lists/massSuicide.py

@@ -1,16 +1,16 @@
 # code to find the order of people how they are going to suicide.
-# In "n" people who are going to suicide, here every "mth" person does it.
+# List 'a' people who are going to suicide. Eevery "mth" person jumps one after another.
 # you have to find out the order in which people commit suicide.
 
-n=10
+
+a = range(0,10)
 m=3
-a = []
-for i in range(n):
-  a.append(i)
+
 s = ""
 i = 0
+
 while(len(a)>0):
-  i = (i + m - 1)%len(a)
-  s += str(a[i]) + " "
-  a.remove(a[i])
-print (s)
+	i = (i + m - 1)%len(a)
+	s += str(a[i]) + " "
+	a.remove(a[i])
+	print (s)

Lists/max 3 num prod.py

@@ -1,3 +1,6 @@
+""" Given a list of integers, find max 3 numbered product"""
+
+
 import sys
 
 def solution(lis):