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You are given a m x n 2D grid initialized with these three possible values.
-1 - A wall or an obstacle.0 - A gate.INF - Infinity means an empty room. We use the value 231 - 1 = 2147483647 to represent INF as you may assume that the distance to a gate is less than 2147483647.Fill each empty room with the distance to its nearest gate. If it is impossible to reach a gate, it should be filled with INF.
For example, given the 2D grid:
INF -1 0 INF INF INF INF -1 INF -1 INF -1 0 -1 INF INF
After running your function, the 2D grid should be:
3 -1 0 1 2 2 1 -1 1 -1 2 -1 0 -1 3 4
此题解法与
public void WallsAndGates(int[,] rooms) { int row = rooms.GetLength(0); int col = rooms.GetLength(1); for(int i = 0;i< row;i++) { for(int j =0;j< col;j++) { if(rooms[i,j] == 0) { DFS(rooms, i+1,j,row,col, 0 ); DFS(rooms, i-1,j,row,col, 0 ); DFS(rooms, i,j-1,row,col, 0 ); DFS(rooms, i,j+1,row,col, 0 ); } } } return; } private void DFS(int[,] rooms, int x,int y, int row,int col,int sentinel) { if(x<0 || x>= row) return; if(y<0 || y>= col) return; if(rooms[x,y] <= 0) return; if(rooms[x,y] < sentinel+1) return; rooms[x,y] =sentinel+1; DFS(rooms, x+1,y,row,col, rooms[x,y] ); DFS(rooms, x-1,y,row,col, rooms[x,y] ); DFS(rooms, x,y-1,row,col, rooms[x,y] ); DFS(rooms, x,y+1,row,col, rooms[x,y] ); }
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原文地址：http://www.cnblogs.com/renyualbert/p/5863366.html
