Leetcode Pattern:

https://techdevguide.withgoogle.com/paths/data-structures-and-algorithms/

Fundamentals

To find the greatest amount of success when practicing, it is highly recommended to know the methods and runtimes of the following data structures and their operations:

• Arrays
• Maps
• Linked Lists
• Queues
• Heaps
• Stacks
• Trees
• Graphs

In addition, you should have a good grasp on common algorithms such as:

Breadth-first search

• Depth-first search
• Binary search
• Recursion

Leetcode pattern:

1. Slide Window Pattern

def maxSumSubarray(arr, k):
    n = len(arr)
    if n < k:
        return None
    
    # Tính tổng của k phần tử đầu tiên
    window_sum = sum(arr[:k])
    max_sum = window_sum
    
    # Di chuyển cửa sổ và cập nhật tổng
    for i in range(n - k):
        window_sum = window_sum - arr[i] + arr[i + k]
        max_sum = max(max_sum, window_sum)
    
    return max_sum

# Sử dụng
arr = [1, 4, 2, 10, 23, 3, 1, 0, 20]
k = 4
print(maxSumSubarray(arr, k))  # Output: 39