Freaks City

Counting Palindromic Substrings This section addresses the problem of counting all palindromic substrings within a given string, similar to LeetCode problem 647. Problem Description Given a string s, determine and return the total count of palindromic substrings. A substring is a contiguous sequence of charcaters. A palindromic string reads the ...

LeetCode 257: Binary Tree All Paths Termination Condition Considerations The statement if (root == nullptr) return; serves multiple critical purposes in recursive tree algorithms: Primary Function Guard When placed in the main function provided by LeetCode, this check handles the empty tree case. If an empty tree is passed to the main function, ...

590. N-ary Tree Postorder Traversal Approach: Right-to-left, then root-to-left. Use a stack with a visited set to track processed nodes. class Node: def __init__(self, val=None, children=None): self.val = val self.children = children def postorder(root): if not root: return [] stack = [root] result = [] ...

The Trapping Rain Water problem, as featured on LeetCode 42, asks you to calculate the total amount of water that can be trapped after raining, given an elevation map represented by an array of non-negative integers. Each element in the array represents the height of a bar with a width of 1. Water can be trapped between bars of higher elevation ...

Two Sum Use a hash map to store each number’s index. For every element, check if the complement (target - current) exists in the map. class Solution: def twoSum(self, nums: List[int], target: int) -> List[int]: seen = {} for idx, val in enumerate(nums): complement = target - val if complement in se ...

Swapping Adjacent Nodes in a Linked ListSwapping nodes in pairs requires careful pointer manipulation to maintain the integrity of the list structure. The core idea involves processing two nodes at a time, reversing their connection order while preserving links to neighboring nodes.A dummy header node simplifies edge cases by providing a consis ...

Intersection of Linked Lists Problem Link LeetCode 160 Problem Statement Given the heads of two singly linked lists, headA and headB, return the node at which the two lists intesrect. If there is no intersection, return nullptr. The linked lists must retain their original structure after the function returns. You are not allowed to modify th ...

Problem Description You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order, and each node contains a single digit. Add the two numbers and return the sum as a linked list. You may assume the two numbers do not contain any leading zero, except the number 0 itself. Examples Example ...

Arrays and Strings Merging Sorted Arrays Naive Merge and Sort class Solution { public: void combineArrays(vector<int>& arr1, int m, vector<int>& arr2, int n) { for(int i = 0; i < n; ++i) { arr1[m + i] = arr2[i]; } sort(arr1.begin(), arr1.end()); } }; Two-Pointer Forward Merg ...

Unique Substrings in Wraparound String Given a string p, find the number of unique non-empty substrings of p that are also substrings of the infinite wraparound string "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz...". The infinite string repeats the alphabet sequence cyclically. DP Solution: We'll use a DP array where dp[i] r ...