let it begin

.gitignore

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+# Ignore all
+*
+
+# Unignore anything with extention
+!*/
+!*.*
+
+# Except for the following
+*.DS_Store
+*.class

concepts/1_arrays_and_strings/unique_string/unique.java

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+public class unique {
+
+	public static void main(String[] args) {
+		System.out.println(is_unique( "abcdefghijklmnopqrstuvwxyz" )); // true
+		System.out.println(is_unique( "abcdefghijklmnopqrstuvwxyzz" )); // false
+		System.out.println(is_unique( "aa" )); // false
+		System.out.println(is_unique( "aba" )); // false
+		System.out.println(is_unique( "aaaaaaaaaaaaaaaaaaaaaaaaaaa" )); // false
+		System.out.println(is_unique( "  " )); // false
+		System.out.println(is_unique( " " )); // true
+	}
+
+	public static boolean is_unique(String str) {
+		if (str.length() > 128) { // assume ascii, not unicode
+			return false;
+		}
+
+		boolean[] alf = new boolean[128];
+		for (int i = 0; i < str.length(); i++) {
+			int val = str.charAt(i);
+			if (alf[val]) {
+				return false;
+			}
+			alf[val] = true;
+		}
+		return true;
+	}
+
+}

concepts/1_arrays_and_strings/unique_string/unique.php

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+<?php
+
+echo is_unique( 'abcdefghijklmnopqrstuvwxyz' ) . "\n"; // true
+echo is_unique( 'abcdefghijklmnopqrstuvwxyzz' ) . "\n"; // false
+echo is_unique( 'aa' ) . "\n"; // false
+echo is_unique( 'aba' ) . "\n"; // false
+echo is_unique( 'aaaaaaaaaaaaaaaaaaaaaaaaaaa' ) . "\n"; // false
+echo is_unique( '  ' ) . "\n"; // false
+echo is_unique( ' ' ) . "\n"; // true
+
+function is_unique( $string ) {
+	$strlen = strlen( $string ); // calculate once instead of twice
+
+	if ( 128 < $strlen ) { // TODO understand the difference between ascii and unicode
+		return 'false';
+	}
+
+	$alf = array();
+	for ( $i = 0; $i <= $strlen; $i++ ) { // not foreach
+		$char = substr( $string, $i, 1 );
+
+		if ( ! $alf[ $char ] ) { // true (already set)
+			$alf[ $char ] = 'true';
+		} else { // false
+			return 'false';
+		}
+	}
+
+	return 'true';
+}

concepts/1_arrays_and_strings/unique_string/unique.py

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+def is_unique( str ):
+	strlen = len( str );
+
+	if strlen > 128:
+		return;
+
+	checker = []
+
+	for letter in str:
+		checker.append( letter );
+
+	if len(checker) > len(set(checker)):
+		return 'false'
+
+	return 'true'
+
+print is_unique("abcdefghijklmnopqrstuvwxyz"); # true
+print is_unique("abcdefghijklmnopqrstuvwxyzz"); # false
+print is_unique("aa"); # false
+print is_unique("aba"); # false
+print is_unique("aaaaaaaaaaaaaaaaaaaaaaaaaaa"); # false
+print is_unique("  "); # false
+print is_unique(" "); # true

concepts/2_linked_lists/1_single_linked/single.c

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+// gcc -o single single.c
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+struct node {
+	int data;
+	int key;
+	struct node *next;
+};
+
+struct node *head = NULL;
+struct node *current = NULL;
+
+int main(void) {
+	printf("Original List: ");
+	printf("Coming Soon!\n");
+	return 0;
+}

concepts/2_linked_lists/1_single_linked/single.java

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+import java.util.*;
+
+public class single {
+	public static void main(String args[]) {
+		LinkedList<String> ll = new LinkedList<String>(); // You should use <String> here
+
+		// add
+		ll.add("J");
+		ll.add("U");
+		ll.add("S");
+		ll.add("T");
+		ll.add("I");
+		ll.add("C");
+		ll.add("E");
+		ll.addLast("Parsons");
+		ll.addFirst("David");
+		ll.add(1, "to the");
+		ll.addLast("III");
+		ll.addLast("III");
+		System.out.println("Linked List after add: " + ll);
+
+		// remove
+		ll.remove("III"); // this only removes one of the III node's above
+		ll.remove(1); // remove from position 1 (the second node)
+		System.out.println("Linked List after remove: " + ll);
+
+		// remove first and last
+		ll.removeFirst();
+		ll.removeLast();
+		System.out.println("Linked List after removing first and last: " + ll);
+
+		// get and set a value
+		Object temp = ll.get(2);
+		ll.set(2, (String) temp + " is same same but different but still same");
+		System.out.println("Linked List after changing second element: " + ll);
+	}
+}

concepts/2_linked_lists/1_single_linked/single_simple.py

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+# Empty list
+thelist = []
+
+# add values to list
+for i in range(0, 6):
+	thelist.append(i) # add value to array
+
+thelist.append(1234)
+thelist.append(1235)
+thelist.append(1236)
+thelist.append(1237)
+thelist.append(1238)
+thelist.append(1239)
+
+# print list
+for i in thelist:
+	print "Current Value: %d" % i

language/php/preg/preg.php

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+<?php
+
+$input = '[wibbitz id="b40d336b69af74f6ca51416b177a23858" autoplay="false"]';
+
+if ( preg_match( '\[[a-z]+.*\]', $input ) ) {
+	echo 'pass';
+} else {
+	echo 'fail';
+}

language/php/preg/strpos.php

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+<?php
+
+$input = '[wibbitz id="b40d336b69af74f6ca51416b177a23858" autoplay="false"]';
+
+if ( 0 === strpos( $input, '[' ) && strlen( $input ) - 1 === strpos( $input, ']' ) ) {
+	echo 'pass';
+} else {
+	echo 'fail';
+}

language/php/preg/substr.php

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+<?php
+
+$input = '[wibbitz id="b40d336b69af74f6ca51416b177a23858" autoplay="false"]';
+
+if ( '[' === substr( $input, 0, 1 ) && ']' === substr( $input, -1 ) ) {
+	echo 'pass';
+} else {
+	echo 'fail';
+}