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This is essentially what a program was, a love letter from the programmer to the hardware, full of the intimate details known only to partners in an affair. Michael Marcotty

LeetCode Problems

Goal:

To become proficient in coding; a coding rockstart, by improving both on problem solving as well as coding fluency

Terms and Definitions:

Term	Definition
Substring	A substring is a contiguous sequence of characters within the string.
Subsequence	Subsequence has order but not continuity. Similar to subarray but need not be contiguous but maintains order.
Palindrome	A string is a palindrome when it reads the same backward as forward.
Kadene’s Algorithm	Method to identify maximum subarray in O(N)
Subarray	Subarray has order and continuity. A subarray is a contiguous part of array. An array that is inside another array. For example, consider the array [1, 2, 3, 4], There are 10 non-empty sub-arrays. The subarrays are (1), (2), (3), (4), (1,2), (2,3), (3,4), (1,2,3), (2,3,4) and (1,2,3,4). In general, for an array/string of size n, there are n*(n+1)/2 non-empty subarrays/substrings.
Subset	Subset has neither order or continuity.

Approaches:

Spend time to think about the problem instead of trying to recollect hazy solution based on similar problem solved in the past
Improve thinking ability. When faced with same problem in future, one may not remember the solution and is likely to think the same way as done earlier.

Templates:

Divide and Conquer
- Divide, Gather, and Combine. The work can happen either in divide phase or in the combine phase. Pay attention to the problem and accordingly pick the template.
Decrease and Conquer
- The problem space can be decreased from one end or both ends. It can be decreased in one step or multi step. Array problems are typical candidates
- Dynamic Programming is a special type of decrease and conquer
Transform and Conquer
- The input can be transformed before processing to either heap or binary search tree or other forms where lookup is fast or constant. Check if the problem requires transformation. Array problems are typical candidates
Enhance and Conquer
Recursion Template
Backtracking