Add leetcode tasks (#1)

Let's Code · web-flow · commit 1652e652b916 · 2019-08-22T21:59:15.000+02:00
* Add leetcode task #2

* Add leetcode task #3
diff --git a/leetcode/add_two_numbers.js b/leetcode/add_two_numbers.js
@@ -0,0 +1,41 @@
+// 2. Add Two Numbers
+// https://leetcode.com/problems/add-two-numbers/
+
+var addTwoNumbers = function (l1, l2) {
+  var extra = 0;
+  var prevNode = null;
+  var resultList = null;
+
+  do {
+    var sum = ((l1 && l1.val) || 0) + ((l2 && l2.val) || 0) + extra;
+
+    if (sum >= 10) {
+      extra = Math.floor(sum / 10);
+
+      sum = sum % 10;
+    } else {
+      extra = 0;
+    }
+
+    var newListItem = { val: sum, next: null }
+
+    if (!resultList) {
+      resultList = newListItem
+    }
+
+    if (prevNode) {
+      prevNode.next = newListItem
+    }
+
+    prevNode = newListItem
+
+    l1 = l1 && l1.next
+    l2 = l2 && l2.next
+  } while (l1 || l2);
+
+  if (extra > 0) {
+    prevNode.next = { val: extra, next: null }
+  }
+
+  return resultList;
+}
diff --git a/leetcode/longest_substring_without_repeating_characters.rb b/leetcode/longest_substring_without_repeating_characters.rb
@@ -0,0 +1,36 @@
+# 3. Longest Substring Without Repeating Characters
+# https://leetcode.com/problems/longest-substring-without-repeating-characters
+
+def longest_substring(s)
+  memo = ""
+
+  s.each_char do |char|
+    break if memo.include?(char)
+
+    memo.concat(char)
+  end
+
+  memo
+end
+
+def length_of_longest_substring(s)
+  longest_size = 0
+
+  return s.size if s.size < 2
+
+  while longest_size < s.size
+    substring = longest_substring(s)
+
+    longest_size = substring.size if substring.size > longest_size
+
+    break if longest_size >= s.size
+
+    repetitive = s[substring.size]
+    repetitive_index = substring.index(repetitive)
+    start_from = repetitive_index + 1
+
+    s = s[start_from..-1]
+  end
+
+  longest_size
+end
