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# source: https://www.hackerrank.com/challenges/3d-surface-area/problem
# video: https://youtu.be/tIG0GF2EqjE

def surfaceArea(A):
    n_rows = len(A)
    n_cols = len(A[0])
    total = (n_rows * n_cols) * 2 # top and bottom 
    for row_i in range(n_rows): # O(n)
        for col_i in range(n_cols): # O(m)
            val = A[row_i][col_i]

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# source: https://leetcode.com/problems/combination-sum
# video: https://youtu.be/0Jt9_qKimCU

def combinationSum(candidates, target):
    dp = [[] for _ in range(target + 1)] # len(dp) = target + 1 b/c want to start with 0
    # intitialize with target = 0, must be empty
    dp[0].append([]) # start out as empty list, with sum total = 0

    # since combinations mean order doesn't matter, we should ensure we don't pass over 
    # parts already calculated ("old" ground)

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# source: https://www.hackerrank.com/challenges/find-maximum-index-product/problem?isFullScreen=false
# video: https://youtu.be/z8iSOFUbQUM

# Stack convenience wrapper for list
class Stack():
    def __init__(self):
        self._stack = [] # store internal list
    
    def is_empty(self): # true when stack is empty
        return len(self._stack) == 0

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# video: https://youtu.be/I7RFycpqbDk
from math import ceil, log2

class SegmentationTree():
    def __init__(self, input_list):
        self._input_list = input_list[:] # copy of input_list
        self._init_tree()
        self._is_propogated = True

    def _init_tree(self):

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# source: https://www.hackerearth.com/practice/data-structures/advanced-data-structures/segment-trees/practice-problems/algorithm/distinct-integers-in-range-66eca44b/description/
import re

### SETUP ###
max_int = 5000
MAX_VALUE = (1 << max_int) - 1
re_splitter = re.compile(" ")

def agg_func(val_1, val_2):
    output = val_1 | val_2

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# source: https://www.hackerrank.com/challenges/bear-and-steady-gene
# video: https://youtu.be/eIW7vBWzibE
def extras_available(all_counts, max_nucleotide_count):
    '''Returns True if any nucleotide count is greater than max_nucleotide_count'''
    # loop through all counts
    for counts in all_counts.values():
        # if any count is greater than max_nucleotide_count, return True
        if counts > max_nucleotide_count:
            return True
    # if got past loop, no extras found => return False

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# source: https://www.hackerrank.com/challenges/lilys-homework
# video: https://youtu.be/HmyDuVZoE8Y
def lilysHomework_helper(arr, reverse = False):
    # clone arr, since modifying
    arr = arr[:] # O(n)?
    # arr = [2, 5, 3, 1]
    # store sorted array
    sorted_arr = sorted(arr, reverse = reverse) # O(nlogn)
    #    sorted_arr = [1, 2, 3, 5]
    #              OR [5, 3, 2, 1] if reverse = True

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# source: https://www.hackerrank.com/challenges/gridland-metro
# video: https://youtu.be/H1Qbd652Oig

def gridlandMetro(n, m, k, tracks): # ALTERED NAME TO PLURAL 
    # tracks = [
    #    [row, col_start, col_end],
    #    ...
    # ]
    # sort by col start
    tracks.sort(key = lambda track: min(track[1], track[2])) # O(nlogn)

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# source: https://www.hackerrank.com/challenges/kindergarten-adventures
# video: https://youtu.be/9vcrruySa9s
def sanitize_index(index, n):
    # index already valid
    if 0 <= index and index < n:
        return index
    
    # negative index
    if index < 0:
        return n + index

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// source: https://www.youtube.com/redirect?q=https%3A%2F%2Fwww.hackerrank.com%2Fchallenges%2Fwaiter%2Fproblem%3Fh_r%3Dinternal-search&event=video_description&redir_token=QUFFLUhqbWRvZWVfbjJJUVQ0Q2J0WnpTLTVVUnBPYnFYd3xBQ3Jtc0trUXJ5MGF5UVJ5UlgxakpSQnZsXzB0QXY2bk5INzJ4MmhkRk5YLWUzV1RjLXQzX2xqUFl3LUtUVnhlT29QV0VoY3FhOVVqMDZrZ21JQjRXVEdvbUdHR3BZajllbmNuVGJBMTFtcXY0VWxaMGxyUmt1NA%3D%3D&v=UW-1KB9PFrA
// video: https://www.youtube.com/watch?v=UW-1KB9PFrA&lc=UgyNhlGoJNiMul7Byad4AaABAg
function getPrimes(n){
    const primesStr = "2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97,101,103,107,109,113,127,131,137,139,149,151,157,163,167,173,179,181,191,193,197,199,211,223,227,229,233,239,241,251,257,263,269,271,277,281,283,293,307,311,313,317,331,337,347,349,353,359,367,373,379,383,389,397,401,409,419,421,431,433,439,443,449,457,461,463,467,479,487,491,499,503,509,521,523,541,547,557,563,569,571,577,587,593,599,601,607,613,617,619,631,641,643,647,653,659,661,673,677,683,691,701,709,719,727,733,739,7