Added Find anagrams

Author: ignacio-chiazzo

LeetcodeProblems/Algorithms/Find_Anagrams.js

@@ -0,0 +1,83 @@
+/*
+Find All Anagrams in a String
+https://leetcode.com/problems/find-all-anagrams-in-a-string/
+
+Given two strings s and p, return an array of all the start indices of p's anagrams in s. 
+You may return the answer in any order.
+
+An Anagram is a word or phrase formed by rearranging the letters of a different word or phrase, 
+ypically using all the original letters exactly once.
+
+Example 1:
+
+Input: s = "cbaebabacd", p = "abc"
+Output: [0,6]
+Explanation:
+The substring with start index = 0 is "cba", which is an anagram of "abc".
+The substring with start index = 6 is "bac", which is an anagram of "abc".
+Example 2:
+
+Input: s = "abab", p = "ab"
+Output: [0,1,2]
+Explanation:
+The substring with start index = 0 is "ab", which is an anagram of "ab".
+The substring with start index = 1 is "ba", which is an anagram of "ab".
+The substring with start index = 2 is "ab", which is an anagram of "ab".
+*/
+
+/**
+ * @param {string} s
+ * @param {string} p
+ * @return {number[]}
+ */
+ var findAnagrams = function(s, p) {
+  if(s.length < p.length) { return [] }
+  
+  let start = 0;
+  let end = p.length - 1;
+  let hashBuild = {};
+  let countLeft = p.length;
+  let anagrams = []
+  
+  for(let e = 0; e < p.length; e++) {
+      hashBuild[p[e]] = hashBuild[p[e]] !== undefined ? hashBuild[p[e]] + 1 : 1;  
+  }
+
+  for(let i = start; i < end; i++) {
+      if(hashBuild[s[i]]  !== undefined) {
+          hashBuild[s[i]] = hashBuild[s[i]] - 1;
+          if(hashBuild[s[i]] >= 0) {
+              countLeft--;
+          }
+      }
+  }
+  
+  while(end < s.length) {
+      // check left
+      if(hashBuild[s[end]] !== undefined) {
+          hashBuild[s[end]] = hashBuild[s[end]] - 1;
+          if(hashBuild[s[end]] >= 0) {
+              countLeft--;
+          }
+          if(countLeft == 0) {
+              anagrams.push(start);
+          } 
+      }
+      
+      // check right
+      if(hashBuild[s[start]] !== undefined) {
+          hashBuild[s[start]] = hashBuild[s[start]] + 1;
+          if(hashBuild[s[start]] >= 1) {
+              countLeft++;
+          }
+      }
+      
+      // slide window
+      end++;
+      start++;
+  }
+  
+  return anagrams;
+};
+
+module.exports.findAnagrams = findAnagrams;

LeetcodeProblemsTests/Algorithms/Find_Anagrams_Test.js

@@ -0,0 +1,12 @@
+
+const assert = require('assert');
+var findAnagrams = require('../../LeetcodeProblems/Algorithms/Find_Anagrams').findAnagrams;
+
+function test() {
+  assert.deepEqual([], findAnagrams("AA", "BB"));
+  assert.deepEqual([0,1,2,3], findAnagrams("AAAA", "A"));
+  assert.deepEqual([0,1,2], findAnagrams("abab", "ab"));
+  assert.deepEqual([0,6], findAnagrams("cbaebabacd", "abc"));
+}
+
+module.exports.test = test;

README.md

@@ -30,7 +30,8 @@ To run a specific problem in your console run  `node <problem_file_path>` (e.g.
 | [Clone Graph ](/LeetcodeProblems/Algorithms/Clone_Graph.js)                                                     | Medium | https://leetcode.com/problems/clone-graph/ |
 | [Coin Change ](/LeetcodeProblems/Algorithms/Coin_Change.js)                                                     | Medium | https://leetcode.com/problems/coin-change/ |
 | [Design Circular Deque ](/LeetcodeProblems/Algorithms/Design_Circular_Deque.js)                                 | Medium | https://leetcode.com/problems/design-circular-deque/
-| [Escape The Ghosts ](/LeetcodeProblems/Algorithms/Escape_The_Ghosts.js)                                         | Medium | https://leetcode.com/problems/escape-the-ghosts/ |
+| [Escape The Ghosts](/LeetcodeProblems/Algorithms/Escape_The_Ghosts.js)                                          | Medium | https://leetcode.com/problems/escape-the-ghosts/ |
+| [Find All Anagrams in a String](/LeetcodeProblems/Algorithms/Find_Anagrams.js)                                  | Medium | https://leetcode.com/problems/find-all-anagrams-in-a-string/ |
 | [Generate Parenthesis ](/LeetcodeProblems/Algorithms/Generate_Parenthesis.js)                                   | Medium | https://leetcode.com/problems/generate-parentheses | 
 | [Group Anagrams ](/LeetcodeProblems/Algorithms/Group_Anagrams.js)                                               | Medium | https://leetcode.com/problems/group-anagrams/
 | [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/ |