DSA — Arrays

What is an Array?

A collection of elements stored at contiguous memory locations.

# Creating arrays
arr = [1, 2, 3, 4, 5]
arr = list(range(10))

Array Operations

Operation	Time Complexity
Access	O(1)
Search	O(n)
Insert	O(n)
Delete	O(n)

Basic Operations

# Access
first = arr[0]
last = arr[-1]

# Insert
arr.append(6)
arr.insert(0, 0)

# Delete
arr.remove(3)
popped = arr.pop()

# Search
index = arr.index(4)
exists = 4 in arr

# Sort
arr.sort()
arr.sort(reverse=True)

Array Traversal

# For loop
for i in range(len(arr)):
    print(arr[i])

# For each
for item in arr:
    print(item)

# Enumerate
for i, item in enumerate(arr):
    print(f"Index {i}: {item}")

Common Array Problems

# Find maximum
def find_max(arr):
    max_val = arr[0]
    for num in arr:
        if num > max_val:
            max_val = num
    return max_val

# Reverse array
def reverse_array(arr):
    return arr[::-1]

# Remove duplicates
def remove_duplicates(arr):
    return list(set(arr))

Mini Practice

1. Create and manipulate arrays
2. Implement array search
3. Find maximum and minimum
4. Reverse an array

Up Next

Continue with Strings — string manipulation.