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Manage Your Energey Solution: Google codejam 2013 Round 1A

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Most of us are familiar with google codejam, those who don’t visit https://code.google.com/codejam for more information. This is the first problem from Online Round 1A 2013, top 1000 from this round will be eligible for next online round.

Problem Statement

You’ve got a very busy calendar today, full of important stuff to do. You worked hard to prepare and make sure all the activities don’t overlap. Now it’s morning, and you’re worried that despite all of your enthusiasm, you won’t have the energy to do all of this with full engagement.

You will have to manage your energy carefully. You start the day full of energy – E joulesof energy, to be precise. You know you can’t go below zero joules, or you will drop from exhaustion. You can spend any non-negative, integer number of joules on each activity (you can spend zero, if you feel lazy), and after each activity you will regain R joules of energy. No matter how lazy you are, however, you cannot have more than E joules of energy at any time; any extra energy you would regain past that point is wasted.

Now, some things (like solving Code Jam problems) are more important than others. For the ith activity, you have a value vi that expresses how important this activity is to you. The gain you get from each activity is the value of the activity, multiplied by the amount of energy you spent on the activity (in joules). You want to manage your energy so that your total gain will be as large as possible.

Note that you cannot reorder the activities in your calendar. You just have to manage your energy as well as you can with the calendar you have.
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Bullseye Solution: Google codejam 2013 Round 1A

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Most of us are familiar with google codejam, those who don’t visit https://code.google.com/codejam for more information. This is the first problem from Online Round 1A 2013, top 1000 from this round will be eligible for next online round.

Problem

Maria has been hired by the Ghastly Chemicals Junkies (GCJ) company to help them manufacture bullseyes. A bullseye consists of a number of concentric rings (rings that are centered at the same point), and it usually represents an archery target. GCJ is interested in manufacturing black-and-white bullseyes.

Maria starts with t millilitres of black paint, which she will use to draw rings of thickness 1cm (one centimetre). A ring of thickness 1cm is the space between two concentric circles whose radii differ by 1cm.

Maria draws the first black ring around a white circle of radius r cm. Then she repeats the following process for as long as she has enough paint to do so:

  1. Maria imagines a white ring of thickness 1cm around the last black ring.
  2. Then she draws a new black ring of thickness 1cm around that white ring.

Note that each “white ring” is simply the space between two black rings.

The area of a disk with radius 1cm is π cm2. One millilitre of paint is required to cover area π cm2. What is the maximum number of black rings that Maria can draw? Please note that:

  • Maria only draws complete rings. If the remaining paint is not enough to draw a complete black ring, she stops painting immediately.
  • There will always be enough paint to draw at least one black ring.

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Girl name in the car

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guess the girl name in the car

A girl was driving a car, a guy took a lift from her. He asked her name after he get down
Girl said :- my name is hidden in my car’s number, find if you can. Car number was [ WV733N ] Can you guess the girl’s name now?

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Answer:
It’s NEELUM.

Coins and sandwiches

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Three friends A, B and C went on a trip.
A didn’t carry any food with him but had 13 Coins. B had 6 sandwiches, and C had 7 sandwiches with him (Total 13 Sandwiches).

They decided to share the food equally and in return A would give away all 13 coins to B & C.

How should B & C distribute the money?


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Coins and sandwiches solution

Since they have to share the sandwiches equally, each of them will get 13/3 sandwiches.

Hence the sandwiched contributed by B and C to A.
B: 6 – 13/3 = 5/3
C:7 -13/3 = 8/3

Now A should give the money in the ratio of what he got from B and C, i.e.
5/3:8/3 :: 5:8

Hence B will get 5 and C will get 8 coins.

Guess the room number

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It was the first day of our second semester and we were looking for our hostel room numbers allotted, we saw that one of our friend was already allotted the room number last night and he challenged us to guess his new room number. We gave following answers

135, 780, 785 and 732.

He said, “That’s amazing”, “You’ve each guessed exactly one digit correctly and in its right place!”

Now can you guess what is his room number ?

See Guess the room number puzzle solution

Answer

Answer is 182

How?

explanation

The first digit must be 1 or 7. It can’t be 7 as only one digit is correct in each guess. So it’s 1.

The other digits in guess #1 (i.e. 3 and 5) must be incorrect. Therefore, from guess #3, the second digit is 8.

Guess #4 has a correct digit which must be its third, i.e. 2.

Shopkeeper and duplicate note

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shopkeeper and duplicate note

shopkeeper and duplicate note

A very simple but confusing puzzle.
A lady buys goods worth Rs.200 from a shop. (shopkeeper is selling the goods with zero profit). The lady gives him Rs.1000 note. The shopkeeper gets the change from the next shop and keeps Rs.200 for himself and returns Rs.800 to the lady. Later the shopkeeper of the next shop comes with the Rs.1000 note saying “duplicate” and takes his money back.
How much LOSS did the shopkeeper face?

Check your answer:-

Tried enough already?


See Shopkeeper and duplicate note solution

Answer

The answer is Rs.1000
How?

Solution 1

To get the loss of shopkeeper we can get the profit lady and the other shopkeeper.

Loss of first shopkeeper = (Profit of the lady + Profit of the second shopkeeper)

Profit of the lady = Rs.200(for goods) + Rs.800(for the change she received) = Rs.1000
Profit of the second shopkeeper = Rs.0(as he got his money back)
So the loss of the shopkeeper is = 1000 + 0 = Rs.1000

Solution 2

Second way of looking at is what shopkeeper gave to others and what is took from others

Loss of the shopkeeper = What he gave to others - what he took.

What he took
From Lady: Nothing(as the note was a duplicate one)
From Second Shopkeeper: Rs.1000
What he gave
To Lady:- Rs.200(goods) + Rs.800(change)
To second shopkeeper: Rs. 1000
So the loss = (200 + 800 + 1000) – (1000) = Rs.1000

Inverted cards puzzle

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inverted cards puzzle

inverted cards puzzle

One fine day, Santa and banta were playing cards, but suddenly power went off and they were getting bored. So santa randomly inverted position of 10 cards out of 52 cards(and shuffled it) and asked banta to divide the card in two pile with equal number of inverted cards(number of cards in each pile need not be equal). It was very dark in the room and banta could not see the cards, after thinking a bit banta divided the cards in two piles and quite surprisingly on counting number of inverted cards in both the piles were equal.
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10 prisoners and hats puzzle

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Their are 10 prisoners in a jail for a minor crime, they all request the jail officer to set them free, jail officer agrees to release them tomorrow, saying i will

  1. Make you all stand in a queue in ascending order of your heights(smallest first).
  2. You will not be allowed to turn your head(they have to look straight)
  3. I will put one hat on your head, either BLACK or WHITE in color.
  4. Everyone of you has to tell the color of his hat starting from the tallest prisoner, you can only say BLACK or WHITE.
  5. You all will be released, if and only if at least 9 of you guess your hat’s color correctly.

Can you suggest a strategy to the prisoners to maximize the chances of their release?

10 prisoners and hats puzzle

10 prisoners and hats puzzle

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