Intermediate | Algorithms

Count All Paths from Top left to bottom right in Two Dimensional Array including Diagonal Paths

August 14, 2020August 25, 2014 by Sumit Jain

Objective: Count all the paths from left top corner to right bottom corner in two dimensional array.

Input: Two Dimensional array

Output: No of paths.

Approach :

1. Recursive

Recursive solution to this problem is similar to Print All Paths from Top left to bottom right in Two Dimensional Array

But the Time complexity will be exponential because there will be many sub problems which will be solved again and again to get the final solution. read this : “Dynamic programming vs Recursion

2. Dynamic Programming (Better Solution)

Print All Paths from Top left to bottom right in Two Dimensional Array

May 21, 2020August 13, 2014 by Sumit Jain

Objective: Print all the paths from left top corner to right bottom corner in two dimensional array.

Input: Two Dimensional array

Output: Print all the paths.

Note: At the End of the article you will know what needs to be included if you want to print the diagonal paths as well.

Example:

Approach:

Merge or Combine Two Sorted Linked Lists

August 14, 2020August 12, 2014 by Sumit Jain

Objective: Given two sorted linked lists, objective is to merge both the lists in sorted order.

Input: Two sorted linked list List a, List b.

Example: 

List a : ->2->6->18

Listb: ->1->3->17->19

Merged List: ->1->2->3->6->17->18->19

Approach:

Print All Elements of Two Dimensional Array in Spiral

May 21, 2020August 4, 2014 by Sumit Jain

Objective: This question was asked in Amazon interview for the Software development Engineer position, Write an algorithm to print all the elements of two dimensional array in spiral.
Example :

Input: Two dimensional array

Output: All array elements printed in spiral.

Approach:

Quick Sort Implementation

August 14, 2020August 3, 2014 by Sumit Jain

Objective: Write an algorithm to sort an array in increasing or decreasing order using Quick Sort.

Input: An Array arrA[]

Output: A sorted array.

Approach:

Choose any element from the array and call it as pivot element, Example here we have selected middle element as pivot
Place all the elements smaller than pivot in the left side of pivot.
Place all the elements greater than pivot in the right side of pivot.
Sort left side and right side recursively.

Example:

Valid or Well Formed Parentheses | Part – 1

August 14, 2020July 23, 2014 by Sumit Jain

Objective: You have been asked to Write an algorithm to find Whether Given the Sequence of parentheses are well formed. This question was asked in the Amazon Interview.

Input: A String contains a sequence of parentheses

Output: true or false on whether parentheses are well formed or not

Approach:

Idea is to have two counters, one for open parentheses ‘{‘ and one for close ‘}’
Read one character at a time and increment one of the counters
If any given point of time count of close parentheses is greater than the open one, return false
If at the end both counters are equal, return true

Example: { { } { } } – Well formed

{ { } { = Not well formed