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🧱 Blocked Maze DP

Navigate grid with obstacles • Blocked cells = 0 paths!

Start
End
Blocked
Reachable

📐 DP with Obstacles

if blocked[i][j]:
  dp[i][j] = 0
else:
  dp[i][j] = dp[i-1][j] + dp[i][j-1]
Blocked Cells
0
Reachable
0
Valid Paths
?

💡 Key Insight

When a cell is blocked, it has 0 paths. This propagates: cells that can ONLY be reached through blocked cells also have 0 paths!

🎮 Instructions

Click cells to toggle blocks in Edit mode. Then run DP to see path counts. Start/End cannot be blocked.