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 5 3 Brilliant People There are three genii standing in a row in a room facing the same direction. Thus, the genius at one end can see the two genii ahead of him, the genius in the middle can only see the one genius ahea ... Submitted by Ravi Doable 4.3 4 The Classic Weights & Scale You have 8 lead marbles, one of which is heavier than the rest. What is the minimum amount of “weightings” (i.e. with a see-saw scale) you need to do to guarantee finding the odd one out? Submitted by Valentin Doable 4.3 3 What number is next? What number comes next in this sequence? 4, 20, 56, 120, 220, ? Submitted by Aakash Doable 4.3 7 Burning Rope There are two lengths of rope. Each one can burn in exactly one hour. They are not necessarily of the same length or width as each other. They also are not of uniform width (may be wider in middle th ... Submitted by Ravi Doable 4.3 6 The Female Star My first two letters are a man. The first three a woman. The first four are a brave man. And in whole I am a brave woman. Submitted by Valentin Doable 4.3 18 3 Men and a Hotel Room Three men decided to split the cost of a hotel room. The hotel manager gave them a price of \$30. The men split the bill evenly, each paying \$10, and retired to their room. However, the manager real ... Submitted by Valentin Doable 4.2 8 All Apples On the market, mrs. Jones and mrs. Smith sell apples. Mrs. Jones sells her apples per two for 0.50 euro. The apples of Mrs. Smith are a bit smaller; she sells hers per three for 0.50 euro. At a certa ... Submitted by Valentin Doable 4.0 4 Balloon Business You’re sitting in a stationary car. There’s a helium balloon tied to its floor. You accelerate and, obviously feel like you’re being pushed backwards (against the direction of your acceleration). W ... Submitted by Valentin Doable 4.0 0 Plane In The Wind An airplane flies in a straight line from airport A to airport B and back. It has constant engine speed and no wind. Will its total flight time increase, decrease or stay the same if throughout bot ... Submitted by Valentin Doable 4.0 3 Products Algorithm Given an array A[1...N] of integers, create an array O[1...N] where O[i] = the product of all elements in A except for the ith element. For example, if N = 3, and A = {6, 4, 2}, O = {8, 12, 24} The t ... Submitted by ace25 Doable 4.0 2 The Number Problem What does 3685=? 8809=6 7111=0 2172=0 6666=4 1111=0 3213=0 7662=2 8096=5 9312=1 4444=0 6824=3 9999=4 0345=1 2359=1 5522=0 9884=5 Enjoy, this is quite interesting. Submitted by Ravi Doable 4.0 15 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? Submitted by Valentin Doable 3.9 12 Choose the Next Letter Choose the next letter in the sequence: O T T F F S S ? Submitted by Ravi Doable 3.8 7 Bug's Eye You are a bug sitting in one corner of a cubic room. You wish to walk (not fly) to the extreme opposite corner – the corner furthest from you. Describe the shortest path that you can walk. Submitted by Ravi Doable 3.8 4 Electrical Deaths You and your friend are driving out in the pouring rain one night. It soon becomes much to hard too see, so you stop at closest house possible. When you knock on the door, an old lady welcomes you to ... Submitted by Ravi Doable 3.7