Topic: Two-pointers-question / Level: Advanced

• 491. Find the longest contiguous subarray that sums to a target value.
• 492. Count the number of distinct palindromic substrings in a string.
• 493. Check if a string is a valid identifier.
• 494. Find the maximum number of pairs that sum to a target in a sorted array.
• 495. Implement a function to check if two strings are anagrams of each other.
• 496. Given a string, find the length of the longest substring with at most k distinct characters.
• 497. Count the number of ways to arrange a given string with repeated characters.
• 498. Check if a binary search tree is valid using a stack and two pointers.
• 499. Find the maximum length of a substring that contains at least one character from each set.
• 500. Implement a function to find the maximum length of a contiguous subarray with a sum of zero.
• 501. Determine if a number can be expressed as the sum of three cubes.
• 502. Count the number of substrings that can be formed from a given string with at most k characters.
• 503. Given an array of integers, find the maximum product of any two elements.
• 504. Check if a string can be rearranged to form a valid parentheses sequence.
• 505. Find the smallest substring that contains all characters of another string using the two-pointer technique.
• 506. Implement a function to determine the maximum sum of a subarray that does not contain adjacent elements.
• 507. Count the number of ways to reach the last cell in a grid with obstacles.
• 508. Check if two strings can be made equal by swapping two characters.
• 509. Find the longest increasing subsequence of a sequence of integers.
• 510. Count the number of palindromic substrings in a given string using dynamic programming.
• 511. Given an array, determine if it can be partitioned into two subsets with equal sum.
• 512. Implement a function to find the intersection of two arrays.
• 513. Check if a sequence of characters can be converted into a palindrome using the two-pointer technique.
• 514. Find the maximum area of a rectangle that can be formed from a histogram.
• 515. Count the number of valid combinations of parentheses for n pairs.
• 516. Determine the number of unique paths in a grid with varying costs.
• 517. Given a string, find the longest substring with no repeating characters.
• 518. Check if two strings can be transformed into each other using at most one character swap.
• 519. Find the longest increasing subsequence of a string of characters.
• 520. Count the number of distinct palindromic substrings in a string using the two-pointer technique.

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