Freaks City

Problem DescriptionGiven the head of a linked list, determine the node where a cycle begins. If no cycle exists, return null. The cycle is identified when a node can be reached again by continuously following the next pointer. The solution must not modify the original linked list.Algorithm ExplanationFloyd's Cycle Detection Algorithm, also know ...

977. Squares of a Sorted Array Problem Link on LeetCode Approach: Two Pointers Technique Since the array may contain negative numbers, we use two pointers to compare the squares of the elements from both ends. The left pointer starts at the beginning of the array, and the right pointer starts at the end. The larger square is placed at the curre ...

Node Class Definition The following ListNode class serves as the foundation for all examples in this article: import java.util.Arrays; public class ListNode { int data; ListNode next = null; public ListNode(int data) { this.data = data; } public String toString(ListNode node) { int[] values = new int[calcu ...

In this problem, we are given an array $a$ of length $n$ and a target array $b$ of length $m$. Each element $a_i$ has an associated deletion cost $p_i$. We need to find the minimum cost to transform $a$ in to $b$ using a specific "strange function" $f(a)$, or determine if it is impossible. Condition Analysis The function $f(a)$ genera ...

Swappnig Adjacent Nodes in Pairs Given a linked list, swap every two adjacent nodes and return the head pointer. Only pointer manipulation is allowed; nodde values must remain unchanged. A sentinel node simplifies boundary handling. Maintain a prev pointer positioned immediately before each pair. In every iteration, identify the first node, the ...

Swapping Nodes in PairsApproach: Using a dummy head nodeLogic: Create a dummy head node to simplify the swapping process. Use a current pointer that moves forward two steps at a time. The loop continues as long as there are at least two more nodes to swap.Implementation:/** * Definition for singly-linked list. * struct ListNode { * int v ...

Given $n$ closed intervals on a number line, the objective is to select exactly $m$ intervals such that they share at least one common coordinate point. The cost of a selection is defined as the difference between the maximum length and the minimum length among the chosen intervals. The length of an interval $[l, r]$ is calculated as $r - l$. T ...

24. Swap Nodes in Pairs Problem: Swap adjacent nodes in a linked list pairwise, returnnig the new head. Do not modify node values—only rewire nodes. Approaches: Iterative: Use a dummy head to track the previous node. Adjust pointers for each pair. Recursive: Swap the first two nodes, then recurce on the reamining list. class Solution: ...