How to solve a DSA Problem

How to solve a DSA Problem

There can be various alternative ways to solve a problem

1. The first solution that comes in mind is brute force solution

2. The most efficient solution that consumes least time and space is called optimized solution

3. Every problem has a pattern - Figure out the problem belongs to which pattern

4. Once you have figure out the pattern, for each pattern there are alternative approaches

5. For each approach, you should know 3 things - 

   • Concept - covered in Volume 2

   • Data structure - covered in Volume 2

   • Technique/Strategy - In this Volume we will mainly learn various Strategies and Techniques

6. Sometimes concepts and techniques are overlapping

7. Talking about algorithm, Algorithm is a pseudo code/ implementation of a technique. Sometimes you would already be knowing the algorithm as we will also be discussing some common algorithms

Common Data Structure Problem Patterns

1. Array Reversal / Rotation

2. Sum of Elements in a range for Q Queries

3. Given input is Sorted Array

4. Top/maximum/minimum/closest 'K' Elements among 'n' Elements

5. Need of trying all permutations and Combinations

6. Trees and Graphs problems

7. Maximization and Minimization

8. Find common substring among a set of Strings

9. Search/manipulate a bunch of Strings

10. LinkedList Question without using Extra Space

Common Techniques

prefix sum

carry forward 

sliding window 

2 pointers

recursion 

greedy 

fast and slow pointers

islands(matrix traversal)

merge intervals

cyclic sort

two heaps 

bitwise xor 

topological sort 

0/1 knapsack

pallindromic subsequence 

longest common substring

In place reversal of Linked List

Modified Binary Search

Subsets

K-way Merge

Topological Sort

Common Algos

Insertion Sort

Selection Sort

Bubble Sort

Merge sort

Quick Sort

Binary Search

Breadth First Search

Depth First Search