Algorithms

Sunday, November 3, 2013

Given a linked list, determine if it has a cycle in it.

Follow up:
Can you solve it without using extra space?

Given a linked list, return the node where the cycle begins. If there is no cycle, return null.

Follow up:
Can you solve it without using extra space?

A linked list is given such that each node contains an additional random pointer which

could point to any node in the list or null.

Return a deep copy of the list.

There are N gas stations along a circular route, where the amount of gas at station i is gas[i].

You have a car with an unlimited gas tank and it costs cost[i] of gas to travel from

station i to its next station (i+1). You begin the journey with an empty tank at one of the gas stations.

Return the starting gas station's index if you can travel around the circuit once, otherwise return -1.

Note:
The solution is guaranteed to be unique.

Clone an undirected graph. Each node in the graph contains a label and a list of its neighbors.

OJ's undirected graph serialization:

Nodes are labeled uniquely.

We use # as a separator for each node, and , as a separator for node label and each
neighbor of the node.

As an example, consider the serialized graph {0,1,2#1,2#2,2}.

The graph has a total of three nodes, and therefore contains three parts as separated by #.

First node is labeled as 0. Connect node 0 to both nodes 1 and 2.
Second node is labeled as 1. Connect node 1 to node 2.
Third node is labeled as 2. Connect node 2 to node 2 (itself), thus forming a self-cycle.

Given an array of integers, every element appears twice except for one.

Find that single one.

Note:
Your algorithm should have a linear runtime complexity.

Could you implement it without using extra memory?

Given an array of integers, every element appears three times except for one.
Find that single one.

Note:
Your algorithm should have a linear runtime complexity.
Could you implement it without using extra memory?