#290 is updated

Author: Hamid Gasmi

09-problems/lc_425_word_squares.py

@@ -0,0 +1,80 @@
+"""
+    1. Problem Summary / Clarifications / TDD:
+    
+    2. Intuition:
+        - All words have the same length => the word square length must have the words length
+        
+        wall
+        area
+        lead
+        lean
+        lady
+        
+    3. Complexity Analysis:
+        W the size of a word
+        N the size of the list of words
+        
+        W^W
+        
+        
+"""
+
+class Trie:
+    def __init__(self, words: List[str]):
+        self.root = {}
+        
+        for i in range(len(words)):
+            self.append(words[i], i)
+        
+    def append(self, word: str, idx: int):
+        
+        trie_node = self.root
+        for c in word:
+            if c in trie_node:
+                print(c, idx, trie_node)
+                trie_node['$'].append(idx)
+            else:
+                trie_node[c] = {'$': [idx]}
+            trie_node = trie_node[c]
+        
+    def find(self, pattern:[str]) -> List[str]:
+        
+        node = self.root
+        for c in pattern:
+            if c not in node:
+                return []
+            node = node[c]
+        
+        return node['$']
+                
+class Solution:
+    def wordSquares(self, words: List[str]) -> List[List[str]]:
+        
+        self.square_len = len(words[0])
+        
+        trie = Trie(words)
+        #print(trie.root)
+        #print(trie.find(['b']))
+        
+        all_words_squares = []
+        for word in words:
+            self.find_word_squares(trie, 1, [word], all_words_squares)
+                
+        return all_words_squares
+    
+    def find_word_squares(self, trie: Trie, k: int, square: List[str], all_words_squares: List[List[str]]):
+        if k == self.square_len:
+            all_words_squares.append(square.copy())
+            
+            return
+        
+        prefix = []
+        for word in square:
+            prefix.append(word[k])
+        kth_word_candidates = trie.find(prefix)
+        
+        for word in kth_word_candidates:
+            square.append(word)
+            self.find_word_squares(trie, k + 1, square, all_words_squares)
+            square.pop()
+