add Python/Delete_Operation_for_Two_Strings.py

Author: kumailn

Python/Delete_Operation_for_Two_Strings.py

@@ -0,0 +1,24 @@
+# Question: Given two strings find the minimum number of letters you need to delete from each to get the same strings
+# Solution: Implement a top down or bottom up DP
+# Difficulty: Medium
+
+def minDistance(w1: str, w2: str, store={}) -> int:
+    # Our base cases are, if both strings are the same (this includes when they're both null) return 0 because nothing needs to be 
+    # deleted, if only one of them is non-null, then return the length of it since everything needs to be deleted
+    if w1 == w2: return 0
+    if not w1 or not w2: return len(w1 or w2)
+
+    # If we have this pair of words in our store then just return the deletion distance from that
+    if (w1,w2) in store: return store[(w1,w2)]
+    
+    # If both words start with the same letter, nothing needs to be deleted, so just rerun the function
+    # on the substrings with the first character removed, otherwise try deleting the first letter from each word 
+    # and seeing which one results in the shorter deletion distance
+    if w1[0] == w2[0]: 
+        edit = self.minDistance(w1[1:], w2[1:], store)
+    else:
+        edit = 1 + min(self.minDistance(w1[1:], w2, store), self.minDistance(w1, w2[1:], store))
+
+    # Once the computation is completed, store
+    store[(w1,w2)] = edit
+    return edit

README.md

@@ -131,6 +131,8 @@
 | Climbing Stairs | 1 | 70 | Easy | Dynamic Programming | [Python](Python/Coin_Change.py) |
 | Coin Change | 2 | 518 | Medium | Dynamic Programming | [Python](Python/Number_Of_Islands.py) |
 | Decode Ways | 3 | 91 | Medium | Dynamic Programming | [Python](Python/Decode_Ways.py) |
+| Delete Operation for Two Strings | 4 | [583](https://leetcode.com/problems/delete-operation-for-two-strings/) | Medium | Dynamic Programming | [Python](Python/Delete_Operation_for_Two_Strings.py) |
+
 
 ## 🎨 Design 
 | Title | Reccomended Order # | Leetcode # | Difficulty | Tags | Solution |