Central Linked List - Amazon Top Interview Questions

Problem Statement :

Given a singly linked list node, return the value of the middle node. If there's two middle nodes, then return the second one.

Bonus: Solve using \mathcal{O}(1)O(1) space.

Constraints

n ≤ 100,000 where n is the number of nodes in node

Example 1

Input

node = [0, 1, 2]

Output

1

Solution :

                        Solution in C++ :

int solve(LLNode* node) {
LLNode *fast = node, *slow = node;
while (fast != NULL && fast->next != NULL) {
slow = slow->next;
fast = fast->next->next;
}
return slow->val;
}


                        Solution in Java :

import java.util.*;

/**
* class LLNode {
*   int val;
*   LLNode next;
* }
*/
class Solution {
public int solve(LLNode node) {
LLNode slow = node;
LLNode fast = node;

while (fast != null && fast.next != null) {
slow = slow.next;
fast = fast.next.next;
}
return slow.val;
}
}


                        Solution in Python :

class Solution:
def solve(self, node):
slow = node
fast = node
while fast != None and fast.next != None:
slow = slow.next
fast = fast.next.next
return slow.val


Merging Communities

People connect with each other in a social network. A connection between Person I and Person J is represented as . When two persons belonging to different communities connect, the net effect is the merger of both communities which I and J belongs to. At the beginning, there are N people representing N communities. Suppose person 1 and 2 connected and later 2 and 3 connected, then ,1 , 2 and 3 w

Components in a graph

There are 2 * N nodes in an undirected graph, and a number of edges connecting some nodes. In each edge, the first value will be between 1 and N, inclusive. The second node will be between N + 1 and , 2 * N inclusive. Given a list of edges, determine the size of the smallest and largest connected components that have or more nodes. A node can have any number of connections. The highest node valu

Kundu and Tree

Kundu is true tree lover. Tree is a connected graph having N vertices and N-1 edges. Today when he got a tree, he colored each edge with one of either red(r) or black(b) color. He is interested in knowing how many triplets(a,b,c) of vertices are there , such that, there is atleast one edge having red color on all the three paths i.e. from vertex a to b, vertex b to c and vertex c to a . Note that

Super Maximum Cost Queries

Victoria has a tree, T , consisting of N nodes numbered from 1 to N. Each edge from node Ui to Vi in tree T has an integer weight, Wi. Let's define the cost, C, of a path from some node X to some other node Y as the maximum weight ( W ) for any edge in the unique path from node X to Y node . Victoria wants your help processing Q queries on tree T, where each query contains 2 integers, L and

Contacts

We're going to make our own Contacts application! The application must perform two types of operations: 1 . add name, where name is a string denoting a contact name. This must store name as a new contact in the application. find partial, where partial is a string denoting a partial name to search the application for. It must count the number of contacts starting partial with and print the co

No Prefix Set

There is a given list of strings where each string contains only lowercase letters from a - j, inclusive. The set of strings is said to be a GOOD SET if no string is a prefix of another string. In this case, print GOOD SET. Otherwise, print BAD SET on the first line followed by the string being checked. Note If two strings are identical, they are prefixes of each other. Function Descriptio