feat(leetcode): add No.212

Author: mickey0524

212.Word-Search-II.py

@@ -0,0 +1,72 @@
+# https://leetcode.com/problems/word-search-ii/
+#
+# algorithms
+# Hard (27.72%)
+# Total Accepted:    100,953
+# Total Submissions: 364,212
+# beats 61.83% of python submissions
+
+
+class TrieNode(object):
+    def __init__(self):
+        self.children = [None] * 26
+        self.is_leaf = False
+
+
+class Solution(object):
+    def findWords(self, board, words):
+        """
+        :type board: List[List[str]]
+        :type words: List[str]
+        :rtype: List[str]
+        """
+        trie_root = TrieNode()
+        row, col = len(board), len(board[0])
+
+        for w in words:
+            tmp = trie_root
+            for ch in w:
+                trie_idx = ord(ch) - 97
+                if tmp.children[trie_idx] is None:
+                    tmp.children[trie_idx] = TrieNode()
+                tmp = tmp.children[trie_idx]
+            tmp.is_leaf = True
+
+        def recursive(i, j, root, path):
+            ch = board[i][j]
+
+            if ch == '#':
+                return
+
+            trie_idx = ord(ch) - 97
+            if root.children[trie_idx] is None:
+                return
+
+            path += ch
+            board[i][j] = '#'
+            if root.children[trie_idx].is_leaf:
+                res[0] += path,
+                root.children[trie_idx].is_leaf = False
+
+            if i > 0:
+                recursive(i - 1, j, root.children[trie_idx], path)
+
+            if i < row - 1:
+                recursive(i + 1, j, root.children[trie_idx], path)
+
+            if j > 0:
+                recursive(i, j - 1, root.children[trie_idx], path)
+
+            if j < col - 1:
+                recursive(i, j + 1, root.children[trie_idx], path)
+
+            path = path[:-1]
+            board[i][j] = ch
+
+        res = [[]]
+
+        for i in xrange(row):
+            for j in xrange(col):
+                    recursive(i, j, trie_root, '')
+
+        return res[0]