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4
4
Charlie and the Chocolate Factory
Charlie once visited chocolate factory to buy some chocolates.Chocolate cost Rs. 3 each and he had only Rs. 45.He was disappointed. He wanted more.
But when he reached the factory he was amazed. There
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Easy
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7
7
1978
The year 1978 is such that the sum of the first two digits and the latter two digits is equal to the middle two digits, i.e. 19 + 78 = 97. What is the next year (after 1978) for which this is true?
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Doable
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4
Matchsticks
This is a classic Martin Gardner puzzle.
See the picture - the four matchsticks represent a martini glass and the match head represents an olive. Move just two matches so that the glass is reformed bu
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Doable
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2
Count The Bits
Write a function that counts the number of bits in an integer that are set to 1 that is linear in time complexity in the worst case, but sub-linear on average.
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Doable
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5
5
Partitioning a set
In how many ways can a set of r objects be partitioned into subsets of k objects such that:
all subsets are mutually exclusive
each of k-object subset appears in exactly one of the partitions [Partit
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Hard
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10
2
Odd Pills
Your pharmacist gives you 5 jars filled with pills. The pills contained in each jar have an identical appearance and size (i.e. if you mixed all of the pills you wouldn't be able to tell them apart).
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Doable
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9
18
Multiples of 8 plus 1
Squaring the first several odd numbers reveals the following pattern:
3 squared = 8 + 1
5 squared = 24 + 1
7 squared = 48 + 1
8, 24, and 48 are all multiples of 8. Does this pattern hold for all squa
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Hard
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3
Grey Squares Illusion
Square A is the exact same shade of gray as square B.
It's true, check out the reconstruction.
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Doable
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5
5
Non-Adaptive 12 Identical Balls
Okay - so I posted this puzzle to reddit a few weeks ago and one guy had the following comment:
Same problem, but your solution must be non-adaptive. IOW, specify the weighings that you will make up f
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Hard
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6
4
Sum of Two Prime Numbers
If p, q > 2 are consecutive in set of primes. Since p,q can only be odd number, (p+q) is an even number.
Can (p+q)/2 be prime?
from http://republicofmath.com/
Submitted by MoralMachine
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Easy
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4
11
Gold or silver?
What weighs more, a pound of silver or a pound of gold?
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Easy
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17
14
No if() Only abs()
Given two variable a and b, construct a function f(a,b) which return the maximum one in {a,b}.
You can only use +- · / and abs() (to take the absolute value). NO if() is allowed in your construction.
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Submitted by MoralMachine
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Doable
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10
6
Swap Variables in Place without XOR
Suppose you have two variables, a and b. How can you swap their values without using a temporary variable and also without using the bitwise operator XOR?
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Doable
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8
4
The Monty Hall Problem
You’re on a game show, and you’re given the choice of three doors: Behind one door is a car and behind the other two doors are goats.
You pick a door, say No. 1, and the host, who knows what’s behind
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Doable
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7
Two Trains
Two trains (Train A and B) with 200 km between them are travelling towards each other at 100km/h. A mosquito, initially standing on the front of Train A, starts travelling towards Train B at 150km/h. O
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Doable
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