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it's about Problem Solving
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Programming is a tool for Problem Solving
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Input => Algorithms => Output
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Decimal System:
101 => 1*100 + 0*10 + 1*1 = 101 -
Binary System:
101 => 1*2^2 + 0*2^1 + 1*2^0 = 5(in decimal) -
Transistors On/Off for Binary System
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Mapping: ASCII for Letters => Unicode
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Algorithms: Recipes to do something
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first write in Pseudocode
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later translate into real code
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Source Code => Compiler => Machine Code
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use the Debugger!
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Plaintext + Key => Ciphertext
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Ciphertext + Key => Plaintext
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Memory = like Lockers => PC has to look into it first
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sorted vs. unsorted
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Big O Notation:
- constant: c
- logarithmic: log n - binary search in sorted list
- linear: n - linear search
- linearithmic: n log n - merge sort
- quadratic: n^2 - bubble, selection, insert sort
- exponential: c^n - travelling salesman (dynamic programming)
- factorial: n! - travelling salesman (brute force)
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Linear Search: one for one, from left to right: O(n)
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Binary Search: search in the middle, half it every time: O(log n)
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Insertion Sort: insert into right spot on sorted side
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Selection Sort: select the smallest number
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Bubble Sort: bubbling highest number up: O(n^2)
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Merge Sort: Left Half, Right Half, Merge: O(n log n)
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Recursion: Function calls itself until basecase
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Heap, Stack
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Garbage Values: old functions from the Stack
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Pointer, Pointee, Assignment
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char *,malloc -
Hexadecimal: 0-f, 2 blocks of 2^4 bits => decimal: 255 => binary: 1111 1111 => hexa: 0x ff
- struct to create new data structure
- Linked List for dynamic memory allocation
- Stack: LIFO
- Queue: FIFO
- Tree
- Hash Table: Array with Linked List
- Trie: constant time
- set of conventions for communication
- Routing, TCP, IP
- Server: piece of software, that listens for http requests and responds to them
192.168.2.1:80=> IP and TCP Port
- Source Code => Compiler => Byte Code => Interpreter
- named paramters/arguments
- no more pointers
- for in loop
- Flask as web microframework