Add solution for Check if There is a Valid Path in a Grid

camp1/week3/leetcode/check-if-there-is-a-valid-path-in-a-grid.py

@@ -0,0 +1,26 @@
+class Solution:
+    def hasValidPath(self, grid: List[List[int]]) -> bool:
+        directions={1:[(0,-1),(0,1)],2:[(1,0),(-1,0)],
+        3:[(0,-1),(1,0)],4:[(0,1),(1,0)],5:[(-1,0),(0,-1)],
+        6:[(0,1),(-1,0)]
+        }
+        visited=set()
+        def inbound(r,c):
+            return 0<=r<len(grid) and 0<=c<len(grid[0])
+        def dfs(r,c):
+            if r==len(grid)-1 and c==len(grid[0])-1:
+                return True
+            visited.add((r,c))
+            for dr,dc in directions[grid[r][c]]:
+                new_row=dr+r
+                new_col=dc+c
+                if not inbound(new_row,new_col):
+                    continue
+                if (new_row,new_col) not in visited and (-dr,-dc) in directions[grid[new_row][new_col]]:
+                    found=dfs(new_row,new_col)
+                    if found:
+                        return True
+            return False
+        return dfs(0,0)
+
+