gopalanand333/algorithms

what are algorithms, datastructures and their basics

Algorithms

An algorithm is a step by step method of solving a problem. It is commonly used for data processing, calculation and other related computer and mathematical operations. An algorithm is also used to manipulate data in various ways, such as inserting a new data item, searching for a particular item or sorting an item.

Algoritm Comlexity

• Space complexity: How much memory does it require?
• Time comlexity: How much time does it require to complete?

algoritm have a set of input and output values

Algorithm classification

• Serial/Parallel
• Exact/approximate
• Deterministic/non-deterministic

Some common alogorithms

• Search algorithms
• Sorting algorithms
• Computational algorithms
• Collection algorithms

Example: greatest common denominator )GCD of two integers

eg: GCD of 20 and 8 is 8 and 1 def gcd(a,b): while (b !=0): t = b b = t % b return a print(gcd(10,20))

Algorithm performance

• Measure how an algorithm responds to dataset size

Big-O notation

• Classifies performance as the input size grows
• "O" indicates the order of operation: Time Scale to perform an operation
• Many algo have more than one big O values.

Common Big-O Terms

• O(1) Constant Time (looking up single element in array)
• O(log n) - Lograthmic (finding an item in a sorted array with binary search)
• O(n)- Linear time (searching in an unsorted array)
• O (n log n)- Log-linear (Complex sorting alogs like heap and merge sort)
• o(n^2)- Quadratic (bubble sort, selection sort)