CPython 3.10.15Isolated Sandbox

Online Python Compiler — Write & Run Python 3 Online

Veyrai's Online Python Compiler executes CPython 3.10 inside a high-performance sandboxed cloud container. Perfect for practicing LeetCode problems, testing Pythonic idioms (list comprehensions, generators, collections), processing standard input with sys.stdin or input(), and preparing for Python engineering interviews.

Example:

Execution Output

Click "Run (Ctrl+Enter)" to compile and execute your Python program in the isolated sandbox.

How to Use the Online Python Compiler

Clean Indentation

Python uses indentation (4 spaces) rather than braces to define code blocks. The Monaco editor automatically formats your indentation as you type.

Interactive Input Support

Use Python's built-in input() function. Supply your input line by line inside the Standard Input (stdin) panel before executing.

Built-In Standard Library

Import any standard library module: collections, itertools, heapq, math, bisect, json, and re are immediately available with zero installation.

Complexity Feedback

Veyrai's complexity analyzer automatically scans your code for nested iterations, recursion depth, and auxiliary data structures to estimate Big-O complexity.

Python Code Examples & Algorithms

Each example is verified to run in our production CPython 3.10.15 runtime. Click "Load in Editor" to test and modify any example above.

1. Interactive Input & Dictionary Operations

Read input from stdin and format it using Python 3 f-strings and dictionaries.

Time: O(1)

def analyze_city(city_name):
    tech_hubs = {
        "Bangalore": "Silicon Valley of India",
        "Hyderabad": "Cyberabad & High-Tech Core",
        "Pune": "Automotive & Engineering Hub",
        "Delhi-NCR": "Consumer Tech & Unicorns",
    }
    info = tech_hubs.get(city_name, "Emerging Engineering Hub")
    return f"City: {city_name} -> {info}"

user_city = input().strip()
print(analyze_city(user_city))

2. Valid Palindrome (Two-Pointer Technique)

Check if a string is a palindrome considering alphanumeric characters only in O(N) time and O(1) space.

Time: O(N)

def is_palindrome(s: str) -> bool:
    left, right = 0, len(s) - 1
    
    while left < right:
        while left < right and not s[left].isalnum():
            left += 1
        while left < right and not s[right].isalnum():
            right -= 1
            
        if s[left].lower() != s[right].lower():
            return False
            
        left += 1
        right -= 1
        
    return True

test_cases = [
    "A man, a plan, a canal: Panama",
    "race a car",
    "Was it a car or a cat I saw?",
]

for tc in test_cases:
    print(f"'{tc}' -> Palindrome: {is_palindrome(tc)}")

3. Merge Overlapping Intervals (Sorting)

Sort and merge overlapping intervals—one of the most frequent FAANG interview algorithmic challenges.

Time: O(N log N)

def merge_intervals(intervals):
    if not intervals:
        return []
        
    # Sort by start interval time
    intervals.sort(key=lambda x: x[0])
    merged = [intervals[0]]
    
    for current in intervals[1:]:
        prev = merged[-1]
        if current[0] <= prev[1]:
            # Overlapping: merge by updating the end time
            prev[1] = max(prev[1], current[1])
        else:
            merged.append(current)
            
    return merged

intervals = [[1, 3], [2, 6], [8, 10], [15, 18]]
print("Original Intervals:", intervals)
print("Merged Intervals:  ", merge_intervals(intervals))

Common Python Beginner Mistakes & Fixes

Mutable Default Arguments ('def func(data=[])')

Default parameter values are evaluated once when the function is defined, not on every call. Modifying a mutable default list persists changes across calls.

Fix: Use 'def func(data=None): if data is None: data = []'.

Modifying a List While Iterating Over It

Removing or adding items while iterating directly over a list shifts indices, causing elements to be skipped or loops to behave unpredictably.

Fix: Iterate over a shallow copy 'for item in data[:]:' or use list comprehensions.

Using '==' for Identity Instead of 'is'

'==' checks value equality, whereas 'is' checks object identity (memory location).

Fix: Use 'is' only for singletons like 'if var is None:' and '==' for data value comparisons.

Environment Specifications

Language: Python
Compiler / Engine: CPython 3.10.15
Standard Input: Supported (stdin)
Isolation Layer: Dockerized Sandbox
Execution Timeout: 8s to 25s max
Guest Access: Allowed (Rate limited)

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