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Update Computer Science.md
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>> **```String Concatenation```**: means that two strings are combined into one using the "r" sign
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> ## Varaibles
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>> Holder for data
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>> We can use words instead of just a single letter
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>> - can store more than just numbers
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>> a place in memory (RAM: random access memory) where it can be stored or referred to
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>> - Name, type, value
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> - Holder for data
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> - We can use words instead of just a single letter
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> - can store more than just numbers
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> - a place in memory (RAM: random access memory) where it can be stored or referred to
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> - Name, type, value
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>> To declare a variable
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>> 1. Name
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@ -109,9 +109,12 @@
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>>> **Remember** ```String``` is not a primitive type
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>> String - object data type
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>> ```equals(String)```
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>> ### Boolean Expressions
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>>> can only have 2 possible value(true or false)
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>>> - compare must be compatible type
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>> - can only have 2 possible value(true or false)
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>> - compare must be compatible type
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>>> |Symbol|Meaning|
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>>> |:-----|:------|
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@ -152,8 +155,8 @@
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> ## Selection statements
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>> allow java to make a decision
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>> depending on decision, program will function differently each time it is run
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> - allow java to make a decision
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> - depending on decision, program will function differently each time it is run
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>> ```java
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>> if(condition){
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>>>```
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>> ### ```=``` vs ```==```
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>>> ```=```: assignment
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>>> ```==```: comparison
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>> - ```=```: assignment
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>> - ```==```: comparison
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>> ### if.... else if.... else
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@ -193,11 +196,11 @@
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>>> }
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>>> ```
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>>> - used when program needs to choose from a variety of situations
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>>> - use else if to specify another condition
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>>> - helps to control the flow of your program
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>>> - helps make decision when 3 or more conditions must be considered
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>>> - makes program more efficient
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>> - used when program needs to choose from a variety of situations
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>> - use else if to specify another condition
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>> - helps to control the flow of your program
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>> - helps make decision when 3 or more conditions must be considered
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>> - makes program more efficient
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>>> ```java
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>>> if(age >= 16){
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>> **```NOT```**: flips the value of a statement
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>> ### Truth Table
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>>> Used to study logic by computer scientists
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>> - Used to study logic by computer scientists
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>>> | X | Y |X OR Y|X AND Y|
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>>> |:--|:--|:-----|:------|
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@ -269,9 +272,9 @@
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>> ```
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>> ### While Loops
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>>> consists of a condition statement that are executed while the condition is true
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>>> types of conditions used in a while statement are the same as in the ```if statement```
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>>> while the condition is true, repeat the statements in the loop
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>> - consists of a condition statement that are executed while the condition is true
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>> - types of conditions used in a while statement are the same as in the ```if statement```
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>> - while the condition is true, repeat the statements in the loop
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>>> ```java
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>>> while(num <= 10){
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>>> }
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>>> ```
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>>> the program continues repeating until the num is greater than 10
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>>> there may be times when you may want to specify more than one condition
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>>> no limit to the number of conditions, but should limit to 2 or 3
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>>> can combine conditions(logical statements) using ```&&``` and ```||``` conditional operators
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>> - the program continues repeating until the num is greater than 10
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>> - there may be times when you may want to specify more than one condition
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>> - no limit to the number of conditions, but should limit to 2 or 3
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>> - can combine conditions(logical statements) using ```&&``` and ```||``` conditional operators
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>>> ```java
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>>> while(num >= 1 && num <= 10){ // runs until num is between 1 and 10
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>> ### For Loops
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>>> include three distinct statements separated by semicolon
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>>> first statement declares the counter variable
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>>> second statement specifies exit condition
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>>> third statement increments the counter variable after each iteration of the loop
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>>> counter variable only exists within loop
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>> - include three distinct statements separated by semicolon
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>> - first statement declares the counter variable
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>> - second statement specifies exit condition
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>> - third statement increments the counter variable after each iteration of the loop
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>> - counter variable only exists within loop
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>>> ```while``` and ```for``` loop: - may not need to run if condition is false
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>>> ```
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>> ### Accumulator
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>>> variables that add any value to a sum or total
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>>> realize the need for the variable
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>>> declare the variable
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>>> initialize it (give it a start value, usually 0)
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>>> accumulate the value in a loop (add the value to the variable)
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>> - variables that add any value to a sum or total
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>> - realize the need for the variable
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>> - declare the variable
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>> - initialize it (give it a start value, usually 0)
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>> - accumulate the value in a loop (add the value to the variable)
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>> ### Do while Loop
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>>> They must runu minimum once
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>>> They must run minimum once
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>>> After running once, it checks the continue condition at the end of the iteration
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>>> ```java
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@ -390,9 +393,101 @@
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> ```Arrays```: a data structure that allow you to hold multiple pieces of data, in a single object
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> - hold a predetermined number of elements
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> - must be same type
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> ``` java
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> int, String, char, boolean, double, complex types
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> ```
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> - [] - square brackets means index
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> - arrays always start at 0 index
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> - must be assigned a fixed size
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> - use counted loop with array to do things
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> ## Example:
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>> ```java
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>> // declare an array of 5 integer
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>> int [] numArray = new int[5];
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>> // set the 0 index of numArray to 123
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>> numArray[0] = 123;
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>> // get the array size
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>> int arraySize = numArray.length;
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>> ```
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> ### Mid - program initialization of arrays
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> - can declare the array at the beginning ant set size
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> - All variable and arrays must be declared at the beginning of the program for proper conventions
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>> ```java
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>> // declare variables and array
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>> String[] names;
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>> int numValues;
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>> System.out.println("How many names?");
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>> numValues = scan.nextInt();
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>> // initialize array
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>> names = new String[numValues];
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>> ```
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# Unit 3: Sorting
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- ```sorting```: the process of arranging a list of items into a well-defined order
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- final list rearrangement of the original list
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> ## Bubble Sort
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> - when x numbers in array, loop x - 1 times
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> - The bubble sort algorithm works by swapping adjacent pairs in the list until all adjacent pairs are sorted in order, at which the entire list is sorted
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> - by making passes through the array, each pass moves from left to right
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> - the first pass compares element 1 and element 2 and swaps them if they are out of order, then compares element 2 and element 3 and swaps them if they are out of order, and so on
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> - the largest element is moved to the right
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> - for a length of n, there are n - 1 passes
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>> |Pass 1|Pass 2|Pass 3|Pass 4|
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>> |:-----|:-----|:-----|:-----|
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>> |```3 6``` 5 4 2|```3 5``` 4 2 6|```3 4``` 2 5 6|```3 2``` 4 5 6|
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>> |3 ```6 5``` 4 2|3 ```5 4``` 2 6|3 ```4 2``` 5 6|2 3 4 5 6|
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>> |3 5 ```6 4``` 2|3 4 ```5 2``` 6|3 2 4 5 6|
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>> |3 5 4 ```6 2```|3 4 2 5 6|
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>> |3 5 4 2 6|
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>> |Number of Elements|Number of Passes|Number of Comparisons|
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>> |:-----------------|:---------------|:--------------------|
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>> |4|3|6|
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>> |5|4|10|
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>> |6|5|15|
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>> |7|6|21|
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>> |8|7|28|
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>> |9|8|36|
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>> |10|9|45|
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>> |```n```|```n - 1```|```n * (n - 1) / 2```|
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> ## Algorithm
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>> ```
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>> repeat the following n -1 times
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>> for each element in the array, starting at the first element
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>> compare items in current positions with the element in the next position
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>> if item in current position is greater than item in next position then
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>> swap the 2 items using the following steps
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>> temp = current list item
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>> current list item = next list item
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>> next list item = temp
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>> ```
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> ## Code
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>> ```java
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>> // array called list
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>> for (int i = 0; i < list.length - 1; i++){
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>> for(int j = 0; j < list.length - 1 - i; j++){
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>> if(list[j] > list[j + 1]){
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>> int temp = list[j];
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>> list[j] = list[j + 1];
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>> list[j + 1] = temp;
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>> }
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>> }
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>> }
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>> ```
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> ```CompareTo(String)```
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> - result si a ```negative integer``` if this String object lexicographically(alphabetically) precedes the argument string
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> - result is a ```positive integer``` if this string object
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> - result is ```zero``` if the string are equal
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