Browsing the blog archives for February, 2010

Red, Green and Yellow Balls

Question: You are give two red balls, two green balls and two yellow balls. One ball from each color is heavier than the other one. All the heavier balls weigh the same and all the lighter balls weigh the same. You are only provided with a weighing balance. How many tries would it take to […]


Tunnel Trouble

Question: A man needs to go through a train tunnel to reach the other side. He starts running through the tunnel in an effort to reach his destination as soon as possible. When he is 1/4th of the way through the tunnel, he hears the train whistle behind him. Assuming the tunnel is not big […]

First Non-Repeated Character

Question: Write an algorithm to find the first non-repeated character in a string. For example, the first non-repeated character in the string ‘abcdab’ is ‘c’. Answer: Seems trivial enough right? If a character is repeated, we should be able to search the string to determine if that character appears again. So if we go about […]

Number of Ones

Question: Write a function that determines the number of bits set to 1 in the binary representation of an integer. Answer: Going by the brute force approach, it would be easy to come up with the following solution. If the least significant bit of a number is 1, it will return a result of 1 […]

Farmer’s Dilemma

Question: A farmer bought a goat, a wolf and a cabbage from the market. On his way home, he has to cross a river. He has a small boat which only allows him to take one thing with him at a time. The farmer cannot leave the cabbage and the goat together (the goat would […]


Anagrams in an Array of Strings

Question: You are given an array of strings and you are asked to display all the anagrams within the array. For those who don’t know, two words are anagrams if they contain the same characters. Answer: The brute force solution would be to take each string and compare it to every other string in the […]

Permutations of a String

Question: Print all the permutations of a string. Write code in C. Answer: Here is a recursive solution to print all the permutations of a string. However, this solution does not take care of duplicates. It is assumed that there are no duplicates in the string. I left out the implementation of the swap method […]