Find the smallest window in a string containing all characters of another string

Given two strings string1 and string2, find the smallest substring in string1 containing all characters of string2 efficiently.

For Example:

Input string1: “this is a test string”
Input string2: “tist”

Output string: “t stri”

Password Predictor

Danny has a possible list of passwords of Manny’s facebook account. All passwords length is odd. But Danny knows that Manny is a big fan of palindromes. So, his password and reverse of his password both should be in the list.
You have to print the length of Manny’s password and it’s middle character.
Note : The solution will be unique.

Code Chef PRGIFT Aug 14

Today is chef's friend's birthday. He wants to give a gift to his friend. So he was desperately searching for some gift here and there.
Fortunately, he found an array a of size n lying around. The array contains positive integers. Chef's friend likes even numbers very much. So for the gift, chef will choose a consecutive non-empty segment of the array. The segment should contain exactly k even integers. Though it can have any number of odd integers.

CodeChef Code SGARDEN

This time Sheriff gathered all the bandits in his garden and ordered them to line up. After the whistle all bandits should change the order in which they stand.
Sheriff gave all the bandits numbers from 1 to N. For each place i he determined the unique position j. After whistling the bandit staying on position i should run to the j-th position. Sheriff loved seeing how the bandits move around, and he continued whistling until the evening. He finished the game only when he noticed that the bandits are in the same order in which they were standing originally.
Now the Sheriff asks the question: How many times has he whistled?

CodeChef' RRCOPY

Def: 
You had an array of integer numbers. You also had a beautiful operations called "Copy-Paste" which allowed you to copy any contiguous sub-sequence of your array and paste it in any position of your array. For example, if you have array [1, 2, 3, 4, 5] and copy it's sub-sequence from the second to the fourth element and paste it after the third one, then you will get [1, 2, 3, 2, 3, 4, 4, 5] array. You remember that you have done a finite(probably zero) number of such operations over your initial array and got an array A as a result. Unfortunately you don't remember the initial array itself, so you would like to know what could it be. You are interested by the smallest such array. So the task is to find the minimal size(length) of the array that A can be obtained from by using "Copy-Paste" operations.