Collision Pointers

Collision Pointers The two pointers start at two different points, usually the two ends, and move towards each other. This is used in problems like “two sum”, where you need to find two numbers in a sorted array that add up to a target value. This technique is often used on sorted arrays or linked lists.

def two_sum_sorted_array(arr, target):
    left = 0
    right = len(arr) - 1

    while left < right:
        current_sum = arr[left] + arr[right]

        if current_sum == target:
            return (left, right)  # or return the elements: return (arr[left], arr[right])
        elif current_sum < target:
            left += 1  # Move right to increase the sum
        else:
            right -= 1  # Move left to decrease the sum

    return None  # No pair was found

Problem	Topic	Platform
Two Sum II	Two-Pointers	Leetcode
3Sum	Two-Pointers	Leetcode
3Sum Closest	Two-Pointers	Leetcode
4Sum	Two-Pointers	Leetcode
Valid Triangle Number	Two-Pointers	Leetcode
Trapping Rain Water	Two-Pointers	Leetcode
Container With Most Water	Two-Pointers	Leetcode
Partition Array	Two-Pointers	Leetcode
Valid Palindrome	Two-Pointers	Leetcode
Sort Colors	Two-Pointers	Leetcode
Parition Array by Odd and Even	Two-Pointers	Leetcode
Sort Letters by Case	Two-Pointers	Leetcode