438

Author: stevestar888

439-find_all_anagrams_in_a_string.py

@@ -0,0 +1,40 @@
+"""
+https://leetcode.com/problems/find-all-anagrams-in-a-string/
+
+(Is pretty similar to 567. Permutation in String)
+
+Strat: 
+    Sliding window. See explaination from 567.
+
+Stats: O(s + p) time, O(1) space -- one pass in both arrays + storing up to 26 letters in each array
+    Runtime: 80 ms, faster than 94.67% of Python online submissions for Find All Anagrams in a String.
+    Memory Usage: 13.6 MB, less than 94.25% of Python online submissions for Find All Anagrams in a String.
+"""
+class Solution(object):
+    def findAnagrams(self, string, p):
+        """
+        :type s: str
+        :type p: str
+        :rtype: List[int]
+        """
+        result = []
+        letters_needed = [0] * 26
+        for letter in p:
+            letters_needed[ord(letter) - ord('a')] += 1
+            
+        curr_window = [0] * 26
+        for i, letter in enumerate(string):
+            #add to window
+            curr_window[ord(letter) - ord('a')] += 1
+            
+            #delete from window (once curr_window is long enough)
+            if i >= len(p):
+                letter_to_remove = string[i - len(p)]
+                curr_window[ord(letter_to_remove) - ord('a')] -= 1
+            
+            #compare window with target window
+            if curr_window == letters_needed:
+                anagram_start_idx = i + 1 - len(p) #same as i - (len(p) - 1)
+                result.append(anagram_start_idx)
+
+        return result

567-permutation_in_string.py

@@ -1,6 +1,8 @@
 """
 https://leetcode.com/problems/permutation-in-string/submissions/
 
+(Is pretty similar to 438. Find All Anagrams in a String)
+
 Strat:
     Use sliding window. Initially, we preprocess s1 to see how many of each
     letter we need (this becomes our "target" for the sliding window to match).