756

Author: ProHiryu

DFS/traditionalDFS/756.md

@@ -0,0 +1,32 @@
+## Pyramid Transition Matrix
+
+#### Description
+
+[link](https://leetcode.com/problems/pyramid-transition-matrix/)
+
+---
+
+#### Solution
+
+- See Code
+
+---
+
+#### Code
+
+> 最坏情况：O(n^2)
+
+```python
+class Solution:
+    def pyramidTransition(self, bottom: str, allowed: List[str]) -> bool:
+        pool=defaultdict(list)
+        for x in allowed: pool[x[:2]].append(x[2])
+
+        def dfs(bottom):
+            if len(bottom)==1: return True
+            for b in product(*(pool[x+y] for x,y in zip(bottom[:-1],bottom[1:]))):
+                if dfs(b): return True
+            return False
+        
+        return dfs(bottom)
+```