Peter's CodeCrushing

Problem Implement an algorithm to print all valid (e.g., properly opened and closed) combinations of n-pairs of parentheses. EXAMPLE Input: 3 Output: ( ( ( ) ) ) , (()()), (())(), ()(()), ()()()

Problem Write a method to compute all permutations of a string For example: given an input string, "abc", your program should print the following permutations: a ab abc ac acb b ba bac bc bca c ca cab cb cba

Problem Write a method to return all subsets of a set. For example, given set of characters, A = { a, b, c, d} The output should be as blow: ['a', 'ab', 'abc', 'abcd', 'abd', 'ac', 'acd', 'ad', 'b', 'bc', 'bcd', 'bd', 'c', 'cd', 'd']

Problem A magic index in an array A [0. . .n-1] is defined to be an index such that A[i] = i. Given a sorted array of distinct integers, write a method to find a magic index, if one exists, in array A. FOLLOW UP What if the values are not distinct?

Problem A child is running up a staircase with n steps, and can hop either 1 step, 2 steps, or 3 steps at a time. Implement a method to count how many possible ways the a child can run up the stairs.

Problem Write the program that takes the series of intervals and returns a total length covered by the added intervals.  If several intervals intersect, the intersection should be counted only once.  Example:  addInterval(3, 6)  addInterval(8, 9)  addInterval(1, 5)  getTotalCoveredLength() =>; 6  I.e. [1,5) and [3,6) intersect and give a total covered interval [1,6).       [1,6) and [8,9) don't intersect, so the total covered length is a sum of both intervals, that is 5+1=6.                     ______                                        _           _________          0  1  2  3  4  5  6  7  8  9  10      Now, implement the following two methods.       public :      void  addInterval( int  from,  int  to)     {         // implement the methods     }     int getTotalCoveredLength()     {     }

Problem   An efficient way to sort patient files in an array of just 3 types, "high-importance', 'med-importance', 'low-importance', which are in an arbitrary order(unsorted)   The output preference should start with the highest.   example: [high, low, low, med, high, low]

Problem Given the array of integers, A, the target sum, S, and the limit on number of integers to use, K, write the program to return the K integers, whose sum equals, S. Example: A = { 1,2 ,4, 5, 9}, with K = 2, S = 6,  output  = {4, 5}

Problem Write the program to shuffle the deck of cards in statistically random order.

Problem Suppose you have a long flowerbed in which some of the plots are planted and some are not. However, flowers cannot be planted in adjacent plots - they would compete for water and both would die. Given a flowerbed (represented as an array containing booleans), return if a given number of new flowers can be planted in it without violating the no-adjacent-flowers rule  Sample inputs  Input: 1,0,0,0,0,0,1,0,0  3 => true  4 => false  Input: 1,0,0,1,0,0,1,0,0  1 => true  2 => false  input: 0  1 => true  2 => false  public boolean canPlaceFlowers(List flowerbed, int numberToPlace) {  // Implementation here  }

Problem If I type some numbers in my cell, all phone numbers which have these typed numbers in any order should appear, tell data structure for this.  Example: if I type 926 then  932678....  92678...  9777726....  should appear.  Let me clear it through another example  eg: i enter 321, then  o/p(if they are in book)  9344241..  972153....