From 08a675d7b0cf98ff2362818e3f0a4aaad20af1f4 Mon Sep 17 00:00:00 2001
From: Samir Paul <77569653+SamirPaulb@users.noreply.github.com>
Date: Sun, 3 Mar 2024 11:58:00 +0530
Subject: [PATCH] Create 16. Alien Dictionary.py

---
 07_Graph/16. Alien Dictionary.py | 42 ++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 07_Graph/16. Alien Dictionary.py

diff --git a/07_Graph/16. Alien Dictionary.py b/07_Graph/16. Alien Dictionary.py
new file mode 100644
index 00000000..f7859a53
--- /dev/null
+++ b/07_Graph/16. Alien Dictionary.py	
@@ -0,0 +1,42 @@
+# https://www.geeksforgeeks.org/problems/alien-dictionary/1
+# https://www.youtube.com/watch?v=6kTZYvNNyps
+
+class Solution:
+    def findOrder(self,alien_dict, N, K):
+        
+        adj = {char: set() for word in alien_dict for char in word}
+    
+        for i in range(len(alien_dict) - 1):
+            w1, w2 = alien_dict[i], alien_dict[i + 1]
+            minLen = min(len(w1), len(w2))
+            if len(w1) > len(w2) and w1[:minLen] == w2[:minLen]:
+                return ""
+            for j in range(minLen):
+                if w1[j] != w2[j]:
+                    adj[w1[j]].add(w2[j])
+                    break
+    
+        visited = {}  # {char: bool} False visited, True current path
+        res = []
+    
+        def dfs(char):
+            if char in visited:
+                return visited[char]
+    
+            visited[char] = True
+    
+            for neighChar in adj[char]:
+                if dfs(neighChar):
+                    return True
+    
+            visited[char] = False
+            res.append(char)
+    
+        for char in adj:
+            if dfs(char):
+                return ""
+    
+        res.reverse()
+        return "".join(res)
+    
+