Walmart Software Engineer III interview questions

First: 1. Given people's visiting/booking chart for time slots (from-to) into a cyber cafe calculate the maximum computer you need. 2. Calculate the minimum dice rolls you need to win a snake-ladder game denoted by a 2 dimensional matrix where position of snakes and ladder are also given. 3. One more data strucutre algorithm question. Second round: 1. Producer consumer problem and solution 2. Getting most trending hashtag from a stream of tweets efficiently 3. One more multi threading problem which I dont remember. 4. ConcurrentHashMap in java and how does it work and difference b/w other hashmaps. Third round: Short comings from my java round (multi threading) and how would i like to improve my solution. Sine wave sorting from an array of integers. My experience of the interview so far. (He was impressed by the ds algo round and solutions)

An analytical problem solving exercise.