[Leetcode] [JAVA] Surrounded regions

Given a 2D board containing ‘X‘ ‘O‘ and, capture all regions surrounded by ‘X‘ .

A region was captured by flipping all ‘O‘ s into ‘X‘ s-surrounded region.

For example,

x x x xx o o xx x o xx o x x

After running your function, the board should is:

x x x xx x x xx x x xx O x x


The basic idea is that if you label all o that should not be X, then the remaining o is the X.
So, from the O on each side of the matrix to start the graph traversal, into the stack/queue when the corresponding node value from ' O ' into other symbols (I use ' + '), out of the stack/queue of nodes adjacent to the node "O" node to discuss.
When all is done, turn ' o ' into ' X ' and ' + ' to ' o '.
Code:

1  Public classPair {2         intx;3         inty;4Pair (intXinty) {5              This. x =x;6              This. y =y;7         }8     }9      Public voidSolveChar[] board) {Ten         intm=board.length; One         if(m<=2) A             return; -         intN=board[0].length; -          for(inti=0;i<m;i++) { the             if(board[i][0]== ' O ') -DFS (board, I, 0); -             if(board[i][n-1]== ' O ') -DFS (board, I, n-1); +         } -          for(inti=0;i<n;i++) { +             if(board[0][i]== ' O ') ADFS (board, 0, i); at             if(board[m-1][i]== ' O ') -DFS (board, m-1, i); -         } -          for(inti=0;i<m;i++) -              for(intj=0;j<n;j++) { -                 if(board[i][j]== ' O ') inboard[i][j]= ' X '; -                 Else if(board[i][j]== ' + ') toboard[i][j]= ' O '; +             } -     } the      Public voidDfsChar[] BD,intIintj) *     { $Stack<pair> st =NewStack<pair>();Panax NotoginsengBD[I][J] = ' + '; -St.push (NewPair (i,j)); the          +          while(!St.isempty ()) { APair temp =St.pop (); the             if(temp.x>0 && bd[temp.x-1][temp.y]== ' O ') { +bd[temp.x-1][temp.y]= ' + '; -St.push (NewPair (temp.x-1, temp.y)); $             } $             if(temp.y<bd[0].length-1 && bd[temp.x][temp.y+1]== ' O ') { -bd[temp.x][temp.y+1]= ' + '; -St.push (NewPair (temp.x, temp.y+1)); the             } -             if(temp.x<bd.length-1 && bd[temp.x+1][temp.y]== ' O ') {Wuyibd[temp.x+1][temp.y]= ' + '; theSt.push (NewPair (temp.x+1, temp.y)); -             } Wu             if(temp.y>0 && bd[temp.x][temp.y-1]== ' O ') { -bd[temp.x][temp.y-1]= ' + '; AboutSt.push (NewPair (temp.x, temp.y-1)); $             } -         } -}

[Leetcode] [JAVA] Surrounded regions