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Koala and Notebook

idea Starfish .

Consider splitting edges so that the weight of each edge is [0,9] .

Then use the method similar to bucket sorting BFS that will do .

Limak and Shooting Points

The fairy topic .

Consider the full firing sequence . Then shoot in this order . Note that the enumeration is in reverse order , What is known with each shot is which one it ends up hitting monster , Then the obstacles on the path are treated recursively .

The exam should not think of such a second method .

The inspiration from this question is ： Ingenious violence , Cut in from different ways , The difficulty of searching varies greatly .

Super Jaber

The solution does not seem easy to observe .

There are two ways to investigate ：

1. Not through any “ Portal ” , Equivalent to the direct Manhattan distance .
2. Pass through the portal of a certain color , So we can enumerate colors , As “ Transfer station ”

Just preprocess out $dp[i][x][y]$ Indicates that the color is $i$ From any starting point to $(x,y)$ The shortest distance of . The method is obvious .

This question is a great test of observation .

Playoff Restoration

idea Starfish .

meet in the middle + violence + simulation