Differences

This shows you the differences between two versions of the page.

--- spcs:summer2014:teaching_notes [2014/06/18 19:42]
ffpaladin created
+++ spcs:summer2014:teaching_notes [2014/06/18 19:42] (current)
ffpaladin created
@@ Line 1: / Line 1: @@
+====== Software Engineering ======
+===== Math =====
+Prime Numbers
+    * every positive integer can be a product of primes.
+    * prime factorization
+    * Sieve of Eratosthenes
+Permutations/Combinations
+  * Permutations - order matters
+    * with repetition: lock
+      * n^k
+    * without repetition: rainbow
+      * n!/(n-r)!
+  * Combinations - order doesn't matter
+    * with repetition: icecream
+      * (n r)
+      * n!/r!(n-r!)
+    * without repetition: fruit salad
+      * (n+n-r r)
+Bit Manipulation
+    * ^ XOR, ~ boolean NOT
+    * 0110 + 0110 is the same as 0110 * 2, shifting 0110 left by 1.
+    * Multiplying by 2^2 just shifts a number by n
+    * a ^ (~a) is all 1's
+    * bit shifting
+      * arithmetic shift
+      * logical shift
+      * circular rotate
+    * Uses
+      * boolean isPalindrome(int x)
+      * get bit - num & (1 << i) != 0
+      * set bit - num | (1 << i)
+      * clear bit - num & mask,  mask = ~(1 << i)
+      * clear from MSB or 0
+    * powers of 2: http://en.wikipedia.org/wiki/Power_of_two
+  * In Java, all integer types are signed, and the "<<" and ">>" operators perform arithmetic shifts.
+  * Java adds the operator ">>>" to perform logical right shifts,
+  * but because the logical and arithmetic left-shift operations are identical, there is no "<<<" operator in Java.
+===== Basic Data Structures =====
+  * Strings
+    * [[http://pastebin.com/1FAaQhTp|has repeats?]]
+  * Arrays
+  * Linked Lists
+<code java>
+Node deleteNode(Node head, int d) {
+   Node n = head
+   if (n.data == d) {
+      return head.next; // moved head
+   }
+   while (n.next != null) {
+      if (n.next.data == d) {
+         n.next = n.next.next;
+         return head; // head didn't change
+      }
+      n = n.next;
+   }
+   return head;
+}
+</code>
+===== Advanced Data Structures =====
+  * Stacks
+  * Queues
+  * Trees
+    * balanced or unbalanced, full and complete
+    * Tries - Unlike a binary search tree, no node in the tree stores the key associated with that node; instead, its position in the tree defines the key with which it is associated. All the descendants of a node have a common prefix of the string associated with that node, and the root is associated with the empty string.
+  * Graphs - http://pastebin.com/MtJQDqVZ
+    * AdjacencyList
+    * Matrix
+  * HashMap
+<code java>
+  public HashMap<Integer, Student> buildMap(Student[] students) {
+    HashMap<Integer, Student> map = name HashMap<Integer, Student>();
+    for (Student s : students) map.put(s.getId(),s);
+    return map;
+  }
+</code>If you're only interested in the keys, you can iterate through the keySet() of the map:
+<code java>
+Map<String, Object> map = ...;
+for (String key : map.keySet()) {
+    // ...
+}
+</code>
+If you only need the values, use values():
+<code java>
+for (Object value : map.values()) {
+    // ...
+}
+</code>
+Finally, if you want both the key and value, use entrySet():
+<code java>
+for (Map.Entry<String, Object> entry : map.entrySet()) {
+    String key = entry.getKey();
+    Object value = entry.getValue();
+    // ...
+}
+</code>
+One caveat: if you want to remove items mid-iteration, you'll need to do so via an Iterator (see karim79's answer). However, changing item values is OK (see Map.Entry).
+===== Algorithms =====
+  * Recursion - take at least O(n) space, where n is depth of recursive call.
+    * dynamic programming caches results
+  * Sorting
+  * Searching
+  * Big O - http://bigocheatsheet.com/
+    * P - Polynomial Time
+    * NP - Verification is P
+    * NPComplete is NPHard that can be reduced to NP problem (for verification only)
+    * NPHard - Shortest traveling sales person
+===== Design =====
+principles of OOP
+  * Data Abstraction
+  * Encapsulation
+  * Inheritance
+  * Polymorphism
+  * Object-Oriented
+    * factory - cardgame
+    * singleton - restaurant
+    * "does it make sense to call this method, even if no Obj has been constructed yet?" If so, it should definitely be static.
+  * System Design
+   * Memory Limits
+    * order of appearance, hash value, random/arbitrarily
+    * http://www.cs.umd.edu/class/sum2003/cmsc311/Notes/Data/endian.html
+  * Testing
+    * who
+    * what cases
+    * bounds/environmental
+    * failure conditions
+    * how to test
+      * manual/automated
+      * black/whitebox
+    * values
+      * normal
+      * extremes
+      * nulls
+      * strange
+    * troubleshooting
+  * Design Patterns - http://en.wikipedia.org/wiki/Software_design_pattern
+[[teaching notes]]

Teaching

User Tools

Site Tools

Differences

Page Tools