Java Syntax

algorithm.java

public static void main(String[] args) {
  
  // data type and max values
  /*
          width                     minimum                         maximum
  byte:    8 bit                        -128                            +127
  short:  16 bit                     -32 768                         +32 767
  int:    32 bit              -2 147 483 648                  +2 147 483 647
  long:   64 bit  -9 223 372 036 854 775 808      +9 223 372 036 854 775 807
  float:  32 bit                     1.4E-45                 3.402,823,5E+38
  double: 64 bit  1.797,693,134,862,315,7E308                      4.9E-324
  BigInteger   (2 ^ 32) ^ Integer.MAX_VALUE
  */
  
  // Scanner
  Scanner in = new Scanner(System.in);
  
  // Get string
  String time = in.next();

  
  // Get ints
  int a;
  a = in.nextInt();
  int b;
  b = in.nextInt();
  int sum;
  sum = solveMeFirst(a, b);
  System.out.println(sum);
  
  // Array
  int n = in.nextInt();
  int arr[] = new int[n];
  for (int i = 0; i < n; i++) {
    arr[i] = in.nextInt();
  }
  
  // Double Array
  int a[][] = new int[n][n];
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      a[i][j] = in.nextInt();
    }
  }
  
  
  
  // BigInteger
  BigInteger sum = BigInteger.ZERO;
  sum = sum.add(BigInteger.valueOf(5));
  
  // Math
  Math.abs(-5);
  
  // Round up
  (int) Math.ceil((double)a / 100);
  
  // String manipulation
  StringBuilder sb = new StringBuilder();
  sb.append("hello");
  sb.append(" world!");
  
  // String
  String hello = "Hello World";
  // length
  int length = hello.length();
  // concat
  hello = hello.concat(" and Steve!");
  hello = hello + "SDGFSDF";
  // format
  String.format("%d is blah %s", 5, "Steve");
  char c = hello.charAt(5);
  boolean b = hello.equalsWith(hello);
  
  string full = "0123456789";
  String partial = full.substring(3,7); // 3456
  
  // convert string to int
  Integer.parseInt("5454");
  
  // iterate string
  String iterate = "Iterating...";
  for (int i = 0; i < iterate.length(); i++) {
    chat c= s.chartAt(i);
    int ascii = (int) c;
  }
  for(char c : iterate.toCharArray()) {
    // do something with c
  }
  }
  
  // Format Padding
  System.out.format("%02d", 3); // 03
  // %      0                2       d
  // format pad with zero    width   int
  
  
  
  // Array Init
  int arr[] = new int[5]; // array of size 5
  int arr2[] = new int[]{1,2,3};
  int arr3[] = {1,2,3};
  System.out.println(Arrays.toString(arr));
  System.out.println(Arrays.toString(arr2));
  System.out.println(Arrays.toString(arr3));
  
  // init with default value (default value is actually 0 if not specified)
  int temp[] = new int[100];
  Arrays.fill(temp, -1);
  
  // LinkedList
  LinkedList myList = new LinkedList<Integer>();
  myList.add(1);
  myList.add(2);
  System.out.println(myList);
  System.out.println(myList.size());
  // LinkedList implements interfaces Collection, Deque, List, Queue
  
  // Queue
  Queue<Integer> st1=new LinkedList<Integer>();
  /*
            Throws exception    Return value    value
  insert    add(e)              offer(e)        False (full)
  remove    remove()            poll()          null (empty)
  examine   element()           peek()          null (empty)
  
  isEmpty()  - check if empty
  */
  
  // PriorityQueue - MinHeap - top value is minimum
  PriorityQueue<Integer> queue = new LinkedList<Integer>();
  
  // Reversed PriorityQueue - MaxHeap - top value is maximum
   PriorityQueue<Integer> maxPQ = new PriorityQueue<Integer>(20,Collections.reverseOrder());
  
  
  
  // HashMap
  // !!!!! NOT ALLOWED TO USE PRIMITIVE!!!
  HashMap<Character, Integer> count = new HashMap<>();
  
  
}