Most of us struggle quiet a lot while perparing for interviews and specifically in the problem solving part. There are many things to learn and its really gets confusing. This is my mere attempt to organize steps to parpare for such events. I will be keeping this updated with refinements as the time passes.

Place to gather all the basic programs written in order to master the knowledge of datastructures and programs.

All the problems could be classified on the basis of datastructure.

1. String Manipulation Problems

• The total number of substring possible for a string of length n is n * ( n + 1 ) / 2

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For example: string str = "Hello World"; // length == 11

Lets begin by taking 
1 character substring at time: H, e, l, l, o, , W, o, r, l, d. 
Then by taking 2 characters at time: He, el, ll, lo, o , W, Wo, or, rl, ld. 
Then by taking 3 chars: Hel, .. etc.

So the total substring count is 11 + 10 + 9 + .. + 1 and, 
in general, for i from 1 to n, we have n - i + 1 substrings. By summition:

Sigma (n + 1 - i) from i = 1 to n, yields n * (n + 1) - n * (n + 1) / 2 which is n * (n + 1) / 2

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