0130-surrounded-regions.cs

publicclassSolution{
publicvoidSolve(char[][]board){
varn=board.Length;

if(n==0)return;
varm=board[0].Length;

for(inti=0;i<n;i++){
for(intj=0;j<m;j++){
if((i==0||j==0||i==n-1||j==m-1)&&board[i][j]=='O'){
CaptureDfs(board,i,j);
}
}
}

for(inti=0;i<n;i++){
for(intj=0;j<m;j++){
if(board[i][j]=='O'){
board[i][j]='X';
}
}
}

for(inti=0;i<n;i++){
for(intj=0;j<m;j++){
if(board[i][j]=='T'){
board[i][j]='O';
}
}
}
}

privatevoidCaptureDfs(char[][]board,intx,inty){
varn=board.Length;
varm=board[0].Length;

if(x>=n||x<0||y>=m||y<0){
return;
}

if(board[x][y]=='T'||board[x][y]=='X')return;

board[x][y]='T';
CaptureDfs(board,x+1,y);
CaptureDfs(board,x-1,y);
CaptureDfs(board,x,y+1);
CaptureDfs(board,x,y-1);

}
}