Added Longest Substring Problem

Author: ignacio-chiazzo

LeetcodeProblems/Algorithms/Longest_Substring.js

@@ -0,0 +1,62 @@
+/*
+Given a string s, find the length of the longest substring without repeating characters.
+
+Example 1:
+
+Input: s = "abcabcbb"
+Output: 3
+Explanation: The answer is "abc", with the length of 3.
+Example 2:
+
+Input: s = "bbbbb"
+Output: 1
+Explanation: The answer is "b", with the length of 1.
+Example 3:
+
+Input: s = "pwwkew"
+Output: 3
+Explanation: The answer is "wke", with the length of 3.
+Notice that the answer must be a substring, "pwke" is a subsequence and not a substring.
+ 
+
+Constraints:
+
+0 <= s.length <= 5 * 104
+s consists of English letters, digits, symbols and spaces.
+*/
+
+/**
+ * @param {string} s
+ * @return {number}
+ */
+ var lengthOfLongestSubstring = function(s) {
+  if(s.length == 0) { return 0 }
+  
+  var repeatedChars = new Set();
+  var maxLength = 1;
+  var currentMaxLength = 1;
+  var start = 0;
+  var end = 0;
+  repeatedChars.add(s.charAt(start));
+  
+  while(end + 1 < s.length && start < s.length) {
+    if(repeatedChars.has(s.charAt(end + 1))) {
+      if(repeatedChars.has(s.charAt(start))) {
+          currentMaxLength--;
+          repeatedChars.delete(s.charAt(start))
+      }
+        start++;
+    } else {
+      repeatedChars.add(s.charAt(end + 1));
+      currentMaxLength++;
+      if(currentMaxLength > maxLength) {
+          maxLength = currentMaxLength;
+      }
+      end++;
+    }
+  }
+  
+  return maxLength;
+};
+
+module.exports.lengthOfLongestSubstring = lengthOfLongestSubstring;

LeetcodeProblemsTests/Algorithms/Longest_Substring_Test.js

@@ -0,0 +1,12 @@
+const assert = require('assert');
+const lengthOfLongestSubstring = require('../../LeetcodeProblems/Algorithms/Longest_Substring').lengthOfLongestSubstring;
+
+function test() {
+  assert.equal(4, lengthOfLongestSubstring("abcdbcd"));
+  assert.equal(0, lengthOfLongestSubstring(""));
+  assert.equal(1, lengthOfLongestSubstring("b"));
+  assert.equal(1, lengthOfLongestSubstring("bb"));
+  assert.equal(3, lengthOfLongestSubstring("bbacb"));
+}
+
+module.exports.test = test;

README.md

@@ -36,7 +36,8 @@ To run a specific problem in your console run  `node <problem_file_path>` (e.g.
 | [Kth Largest Element in an Array ](/LeetcodeProblems/Algorithms/Kth_Largest_Element_in_an_Array.js)             | Medium | https://leetcode.com/problems/kth-largest-element-in-an-array/ |
 | [Linked List Cycle II ](/LeetcodeProblems/Algorithms/Linked_List_Cycle_II.js)                                   | Medium | https://leetcode.com/problems/linked-list-cycle-ii/ |
 | [Longest Palindromic Substring ](/LeetcodeProblems/Algorithms/Longest_Palindromic_Substring.js)                 | Medium | https://leetcode.com/problems/longest-palindromic-substring/|
-| [Max Area Of Island ](/LeetcodeProblems/Algorithms/Max_Area_Of_Island.js)                                        | Medium | https://leetcode.com/problems/max-area-of-island/ |
+| [Longest Substring Without Reapeating Characters](/LeetcodeProblems/Algorithms/Longest_Substring.js)            | Medium | https://leetcode.com/problems/longest-substring-without-repeating-characters|
+| [Max Area Of Island ](/LeetcodeProblems/Algorithms/Max_Area_Of_Island.js)                                       | Medium | https://leetcode.com/problems/max-area-of-island/ |
 | [Maximal Square ](/LeetcodeProblems/Algorithms/Maximal_Square.js)                                               | Medium | https://leetcode.com/problems/maximal-square/ |
 | [Permutations ](/LeetcodeProblems/Algorithms/Permutations.js)                                                   | Medium | https://leetcode.com/problems/permutations/ |
 | [Permutations II ](/LeetcodeProblems/Algorithms/Permutations_II.js)                                             | Medium | https://leetcode.com/problems/permutations-ii/ |