array-techniques

name	array-techniques
description	Master essential array techniques including two pointers, sliding window, and prefix sums for efficient problem solving with O(n) patterns.
sasmp_version	1.3.0
bonded_agent	01-arrays-lists
bond_type	PRIMARY_BOND
atomic_responsibility	array_pattern_execution
version	2.0.0
parameter_validation	{"strict":true,"rules":[{"name":"array_input","type":"list","required":true,"constraints":{"min_length":0,"max_length":100000}},{"name":"target","type":"integer","required":false},{"name":"window_size","type":"integer","required":false,"constraints":{"min_value":1}}]}
retry_logic	{"max_attempts":3,"backoff_ms":[100,200,400],"retryable_errors":["timeout","memory_exceeded"]}
logging_hooks	{"on_start":true,"on_complete":true,"on_error":true,"log_format":"[ARR-SKILL] {timestamp} | {operation} | {status}"}
complexity_annotations	{"two_pointers":{"time":"O(n)","space":"O(1)"},"sliding_window":{"time":"O(n)","space":"O(1)"},"prefix_sum":{"time":"O(n) build, O(1) query","space":"O(n)"}}

Array Techniques Skill

Atomic Responsibility: Execute array manipulation patterns with optimal complexity.

Two Pointers Pattern

Same Direction (Fast/Slow)

from typing import List

def remove_element(nums: List[int], val: int) -> int:
    """
    Remove all occurrences of val in-place.

    Time: O(n), Space: O(1)

    Args:
        nums: Input array (modified in-place)
        val: Value to remove

    Returns:
        New length of array

    Raises:
        ValueError: If nums is None
    """
    if nums is None:
        raise ValueError("Input array cannot be None")

    write_ptr = 0
    for read_ptr in range(len(nums)):
        if nums[read_ptr] != val:
            nums[write_ptr] = nums[read_ptr]
            write_ptr += 1
    return write_ptr

Opposite Direction (Converging)

def two_sum_sorted(arr: List[int], target: int) -> List[int]:
    """
    Find two indices in sorted array that sum to target.

    Time: O(n), Space: O(1)

    Args:
        arr: Sorted input array
        target: Target sum

    Returns:
        List of two indices, or empty list if not found
    """
    if not arr or len(arr) < 2:
        return []

    left, right = , (arr) - 

     left < right:
        total = arr[left] + arr[right]
         total == target:
             [left, right]
         total < target:
            left += 
        :
            right -= 

     []