Solve: exist

Author: daehyun99

word-search/daehyun99.py

@@ -0,0 +1,33 @@
+from collections import defaultdict
+class Solution:
+    def exist(self, board: List[List[str]], word: str) -> bool:
+        pos = defaultdict(list)
+        for i in range(len(board)):
+            for j in range(len(board[0])):
+                if board[i][j] in word:
+                    tmp = pos.get(board[i][j], [])
+                    tmp.append([i, j])
+                    pos[board[i][j]] = tmp
+
+        paths = pos.get(word[0], [])
+        paths = [[path] for path in paths]
+
+        for w in word[1:]:
+            temp = []
+
+            while len(paths) > 0:
+                path = paths.pop()
+                i , j = path[-1]
+                if ([i, j+1] in pos[w]) and ([i, j+1] not in path):
+                    temp.append(path[:] + [[i, j+1]])
+                if ([i, j-1] in pos[w]) and ([i, j-1] not in path):
+                    temp.append(path[:] + [[i, j-1]])
+                if ([i+1, j] in pos[w]) and ([i+1, j] not in path):
+                    temp.append(path[:] + [[i+1, j]])
+                if ([i-1, j] in pos[w]) and ([i-1, j] not in path):
+                    temp.append(path[:] + [[i-1, j]])
+            paths.extend(temp)
+        for path in paths:
+            if len(path) == len(word):
+                return True
+        return False