Logic riddles

cleverlogicsimpletricky

Three people check into a hotel. They pay $30 to the manager and go to their room. The manager finds out that the room rate is $25 and gives $5 to the bellboy to return. On the way to the room, the bellboy reasons that $5 would be difficult to share among three people, so he pockets $2 and gives $1 to each person. Now, each person paid $10 and got back $1. So they paid $9 each, totalling $27. The bellboy has $2, totalling $29. ) Where is the remaining dollar?
Each person paid $9, totalling $27. The manager has $25 and the bellboy has $2. The bellboy's $2 should be added to the manager's $25 or substracted from the tenant's $27, not added to the tenants' $27.
68.20 %
103 votes
logicmysterydetective

Dave and Brad, two popular politicians, met at a club to discuss the overthrow of their party leader. They each ordered a vodka on the rocks. Brad downed his and ordered another. He then drank his second in a gulp and decided to wait before he ordered a third. Meanwhile, Dave, who was sipping his drink, suddenly fell forward dead. Both men were setup for an assassination. Why did Dave die and Brad live?
Both Dave and Brad were given drinks with poisoned ice cubes. Brad drank his drinks so quickly that the ice didn't have time to melt and release the poison.
68.12 %
349 votes
logicmath

Two words are anagrams if and only if they contain the exact same letters with the exact same frequency (for example, "name" and "mean" are anagrams, but "red" and "deer" are not). Given two strings S1 and S2, which each only contain the lowercase letters a through z, write a program to determine if S1 and S2 are anagrams. The program must have a running time of O(n + m), where n and m are the lengths of S1 and S2, respectively, and it must have O(1) (constant) space usage.
First create an array A of length 26, representing the counts of each letter of the alphabet, with each value initialized to 0. Iterate through each character in S1 and add 1 to the corresponding entry in A. Once this iteration is complete, A will contain the counts for the letters in S1. Then, iterate through each character in S2, and subtract 1 from each corresponding entry in A. Now, if the each entry in A is 0, then S1 and S2 are anagrams; otherwise, S1 and S2 aren't anagrams. Here is pseudocode for the procedure that was described: def areAnagrams(S1, S2) A = new Array(26) A.initializeValues(0) for each character in S1 arrayIndex = mapCharacterToNumber(character) //maps "a" to 0, "b" to 1, "c" to 2, etc... A[arrayIndex] += 1 end for each character in S2 arrayIndex = mapCharacterToNumber(character) A[arrayIndex] -= 1 end for (i = 0; i < 26; i++) if A[i] != 0 return false end end return true end
68.01 %
59 votes
logicmathtricky

A train leaves from Halifax, Nova Scotia heading towards Vancouver, British Columbia at 120 km/h. Three hours later, a train leaves Vancouver heading towards Halifax at 180 km/h. Assume there's exactly 6000 kilometers between Vancouver and Halifax. When they meet, which train is closer to Halifax?
Both trains would be at the same spot when they meet therefore they are both equally close to Halifax.
67.98 %
88 votes
logicmysterystory

A king has no sons, no daughters, and no queen. For this reason he must decide who will take the throne after he dies. To do this he decides that he will give all of the children of the kingdom a single seed. Whichever child has the largest, most beautiful plant will earn the throne; this being a metaphor for the kingdom. At the end of the contest all of the children came to the palace with their enormous and beautiful plants in hand. After he looks at all of the children's pots, he finally decides that the little girl with an empty pot will be the next Queen. Why did he choose this little girl over all of the other children with their beautiful plants?
The king gave them all fake seeds and the little girl was the only honest child who didn't switch seeds.
67.85 %
276 votes
logicsimpleclean

Bill and Stacie are delighted when their new baby, Patrick, is born on February 29th, 2008. They think it's good luck to for him to be born on the special day of the leap year. But then they start thinking about when to celebrate his next birthday. After some thought, they decide that they want to celebrate Patrick's next birthday (when he turns 1) exactly 365 days after he was born, just like most people do. What will be the date of this birthday?
The date of the birthday will be February 28th, 2009. At first it might seem like his birthday should be March 1st, 2009, since February 29th is the day after February 28th in the leap year, while March 1st is the day after February 28th in non-leap years. But this is the wrong way to think about it. The right way to think about it is that 365 days after the day before March 1st is always February 28th, regardless of whether it's a leap year or not. So Patrick's birthday will be February 28th.
67.78 %
126 votes