Sort

C++

For c++, here is official document

sort()

This method sorts elements in the range [first, last).

Result is in ascending order by deflaut.

Introsort.

// sort algorithm example
#include <iostream>     // std::cout
#include <algorithm>    // std::sort
#include <vector>       // std::vector

bool myfunction (int i,int j) { return (i>j); }

int main () {
  int myints[] = {32,71,12,45,26,80,53,33};
  std::vector<int> myvector (myints, myints+8); // 32 71 12 45 26 80 53 33

  // using default comparison (operator <):
  std::sort (myvector.begin(), myvector.begin()+4); //(12 32 45 71)26 80 53 33

  // using function as comp
  std::sort (myvector.begin(), myvector.end(), myfunction); //80 71 53 45 33 32 26 12

  // print out content:
  std::cout << "myvector contains:";
  for (std::vector<int>::iterator it=myvector.begin(); it!=myvector.end(); ++it)
    std::cout << ' ' << *it;
  std::cout << '\n';
  return 0;
}

On average, linearithmic in the distance between first and last: Performs approximately N*log₂N

Container comparison

C++ version is c++11. Java version is java se8.

HashTable & HashMap

The HashMap class is roughly equivalent to Hashtable, except that it is asynchronized and permits nulls.

Declaring an array

Both are allow

string argc[];
string[] argc;

Int array

int[] nums = new int[7];
nums[0] = 10;

Rabbit[] racers = new Rabbit[10];//10 empty rabbit array;
racers[0] = new Rabbit("B","F");

arraycopy()

System.arraycopy(nums, 0, nums, 0, nums.length);

Array vs ArrayList

1. An array needs to know its size at the time of creation, arrayList does not.
2. To assign an object in array you must assign it to a specific index.
3. Array use array syntax ([]).
4. ArrayList is parameterized. ArrayList<string>

ArrayList

ArrayList<Flower> flowerList = new ArrayList<Flower>();// <- ArrayList constructor
Flower f = new Flower();
Flower m = new Flower();

flowerList.add(f);
flowerList.add(m);

JavaDocs

JavaDocs is able to easily generate a code “maintenance manual”

A doc comment is made up of two parts – a description and two or more tag.

/**
* Here is description
*
* @tag Comment for tag
*/

Tags

• @author (classes and interfaces only, required)
• @version (classes and interfaces only, required)
• @param (methods and constructors only)
• @return (methods only)
• @exception
• @see
• @since
• @serial (or @serialField or @serialData)
• @deprecated

JDK Docs

External documentation can be created with javadoc

Class & Object

A class only exists at compile time;

An object only exists at runtime.

Data Encapsulation

Data Encapsulation/information hiding: where the internal state and operation are hidden from others.

The more information Class A knows about Class B, the greater the possibility that changing Class A will adversely affect Class B. In an ideal world, making internal changes to Class A should have no, or very little, effect on other classes.

Basic types

Every type have a default value:

Difference between i++ and ++i

b = 1;
a = b++; // a = 1; b = 2

b = 1;
a = ++b; // a = 2; b = 2

int a = 1;
int res = a++ + a;
// res = 3 ; a = 2.

int a = 1;
int res = a + a++;
// res = 2; a = 2.

int a = 1;
int res = ++a + a;
// res = 4; a = 2.

int a = 1;
int res = a + ++a;
// res = 3; a = 2.

For loop

for(int i=0; i < n ; i++)

This is learning note for MarkDown

Heading 1

or

Heading 1

Heading 2

or

Heading 2

Italic and bold

italic or italic bold or bold italic and bold or italic and bold

Unordered list

• line 1
• line 2
• line 3
  • sub 1
  • sub 2

or

• line 1
• line 2
• line 3
  • sub 1
  • sub 2

Ordered list

1. line 1
2. line 2
   1. sub 1
   2. sub 2
3. line 3

BlockQuotes

Use ‘>’ for a quotes

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