Create Surrounded Regions

Author: elfxwt

Matrix/Surrounded Regions

@@ -0,0 +1,63 @@
+  // 想到了开头，没有想到细节。。。
+  
+  class Solution {
+	  void bfs(int x,int y,vector<vector<char>> &board)
+	  {
+		  queue<int> q;
+		  visited(x,y,board,q);
+		  while(!q.empty())
+		  {
+			  int pos = q.front();
+			  q.pop();
+			  int posX = pos / board[0].size();
+			  int posY = pos % board[0].size();
+			  visited(posX-1,posY,board,q);
+			  visited(posX + 1,posY,board,q);
+			  visited(posX,posY-1,board,q);
+			  visited(posX,posY + 1,board,q);
+
+		  }
+
+	  }
+
+	  void visited(int x, int y,vector<vector<char>> &board,queue<int>&q)
+	  {
+		  const int m = board.size();
+		  const int n = board[0].size();
+		  if(x < 0 || x >= m || y < 0 || y >= n || board[x][y] != 'O')
+			  return;
+		  board[x][y] = '#';  // 这个很聪明~
+		  q.push(x * n + y);
+
+	  }
+
+  public:
+	  void solve(vector<vector<char>> &board) {
+		  if(board.size() <= 0) return;
+		  int n = board.size();
+
+		  int m = board[0].size();
+		  // 上下左右
+		  for(int i = 0;i < m;i++)
+		  {
+			  bfs(0,i,board);
+			  bfs(n-1,i,board);
+		  }
+		  for(int j = 1;j < n-1;j++)
+		  {
+			  bfs(j,0,board);
+			  bfs(j,m-1,board);
+		  }
+		  
+		  for( int i = 0;i < n;i++)
+			  for(int j = 0;j < m;j++)
+			  {
+				  if(board[i][j] == '#')
+					  board[i][j] = 'O';
+				  else
+					  if(board[i][j] == 'O')
+						  board[i][j] = 'X'; 
+			  }
+
+	  }
+  };