tips.yaml

2-D:
    helper row, col: helps to keep track of "count and location" of 1's in matrix
    DFS/ BFS visited: 
        seen = set() 
        visited=[0]*N
        visited=[[for j in range(n)] for i in range(n)]
        flood-fill-algorithm
    Good examples:
        find-islands-maxarea
        maximal_square
    
    
    
Array:
    target sum: 4-subarray-sum-minimum-size, 4-subarray-with-given-sum
    maintain sorted list: heapq (minimum-meeting_rooms)
    queue to popleft: deque (findisland-rotting-oranges)
    
    
String:
    ord(c)  -   to convert strint to integer
    <number>*10 -   to convert string to number (first digit is 0, then actual number)
    
    
Sliding Window:
    https://github.com/dcprakash/codebase/blob/e9d45315727248ec53da54b24f4b54159f2cfe50/String/1-longest-substring-without-repeating-char-easy.py
    
loop and condition:
    /HashTable/hashmap.py
    https://www.tutorialspoint.com/python3/python_while_loop.htm
    
zip:
    parallel iteration https://realpython.com/python-zip-function/
    Python’s zip() function is defined as zip(*iterables). 
    The function takes in iterables as arguments and returns an iterator. 
    This iterator generates a series of tuples containing elements from each iterable.
    zip() can accept any type of iterable, such as files, lists, tuples, dictionaries, sets, and so on.
    
    numbers = [1, 2, 3]
    letters = ['a', 'b']
    zipped = zip(numbers, letters)
    print(list(zipped))  
    # [(1, 'a'), (2, 'b')]
    # output will be equal to the length of the shortest iterable.
    
    # unzip along with the unpacking operator *
    pairs = [(1, 'a'), (2, 'b'), (3, 'c'), (4, 'd')]
    numbers, letters = zip(*pairs)
    print(numbers)
    # (1, 2, 3, 4)
    print(letters)
    # ('a', 'b', 'c', 'd')
    
sentinel nodes:
    usage of temp nodes called sentinel
        remove-linked-list-elements
        
list:
    join:
        list=[]
        "".join(list)
        ".".join(list)      # adds . inbetween each list item
    deep copy:
        nums=[1,3,5,6]
        n=nums[:]
        
stack, queue:
    queue=[]
    queue.pop(0)    # removes first item
    queue.pop()     # removes last item
    queue.pop(-1)     # removes last item
    
    
defaultdict:
    Group-Anagrams
    
    
moving items in place:
    Move-Zero-InPlace
    

filter and map:
    valid-palindrome:
        s="A man, a plan, a canal: Panama"
        alnum=filter(lambda ch: ch.isalnum(), s)
        slower=map(lambda ch: ch.lower(), alnum)
        
split:
    path="root/a 1.txt(abcd) 2.txt(efgh)"
    dir,*files=path.split(' ')
    
lambda:
    find-smallest-divisor-given-threshold
    top-k-frequent-words
    
dict:
    trick1:
        partition_labels:
            s = "ababcbacadefegdehijhklij"
            last = {c: i for i, c in enumerate(S)}
            'a': 8, 'b': 5, 'c': 7, 'd': 14, 'e': 15, 'f': 11, 'g': 13, 'h': 19, 'i': 22, 'j': 23, 'k': 20, 'l': 21}
            
anchor reader writer:
    string_compression