danielrobertson

void dfs(Node r) {
  if(r == null) 
    return; 
  visit(r); 
  r.visited = true; // avoid cycles 
  for(Node n : r.adjacent) {
    if(!n.visited)
      dfs(n); 
  }
}

danielrobertson

// Determine if a binary tree is a binary search tree 
boolean isBst(Node r) {
  return isBst(r, null, null); 
}

boolean isBst(Node r, Integer min, Integer max) {
  if(r == null) 
    return true; 
    
  if((min != null && r.data < min) || (max != null && r.data > max))

danielrobertson

Node reverse(Node n) {
  // maintain previous node, rewriting all pointers to previous
    Node prev = null;
    while(n != null) {
        Node next = n.next;
        n.next = prev;
        prev = n;
        n = next;
    }

danielrobertson

boolean isPalindrome(Node n){
    Node fast = n;
    Node slow = n;

    // push first half onto stack, then compare with second half
    Stack<Integer> s = new Stack<Integer>();
    while(fast != null && fast.next != null) {
        s.push(slow.data);
        slow = slow.next;
        fast = fast.next.next;

danielrobertson

// aabccccaaa -> aabccccaaa
String compressString(String input) {
	StringBuilder compressed = new StringBuilder(); 
	int count = 1; 
	String[] arr = input.split(""); 
	for(int i = 0; i < arr.length; i++) {
		++count; 
		if(i + 1 >= arr.length || !arr[i + 1].equals(arr[i])) {
			compressed.append(arr[i]); 
			compressed.append(Integer.toString(count));

danielrobertson

// pale, ple -> true 
// pales, pale -> true 
// pale, bale -> true 
// pale, bake -> false 
boolean isOneAway(String a, String b) {
	int aLength = a.length(); 
	int bLength = b.length(); 

	int shortIndex = 0; 
	int longIndex = 0; 

danielrobertson

// palindrome will have even letter counts and at most one odd letter count 
boolean isPalindromPermutation(String input) {
  	Map<String, Integer> frequency = new HashMap<String, Integer>(); 
  	for(String s : input.split("")) {
  		if(!frequency.containsKey(s)) {
  			frequency.put(s, 1); 
  		} else {
  			frequency.put(s, 1 + frequency.get(s)); 
  		}
  	}

danielrobertson

// using StringBuffer
boolean isPalindrome(String s) {
    StringBuffer stringBuffer = new StringBuffer(s);
    StringBuffer reverse = new StringBuffer(s);
    reverse.reverse();
    return stringBuffer.toString().equals(reverse.toString());
}

// in place 
boolean isPalindrome(String input) {

danielrobertson

var fs = require('fs');
var parse = require('csv-parse');

var consumed = 0; 
var burned = 0;
var numDays = 0; 

var parser = parse({delimiter: ';'}, function(err, data){
	data.forEach(function(data){
		++numDays; 

danielrobertson

nmap -PN localhost

-----------------------
PORT     STATE SERVICE
631/tcp  open  ipp
1023/tcp open  netvenuechat