lintcode

class Solution {
public:
    /*
     * @param board: board a 2D board containing 'X' and 'O'
     * @return: nothing
     */
    bool flag[220][220];
    vector<pair<int, int>> v;
    const int dir[4][2] = {{0,1}, {1,0}, {0, -1}, {-1, 0}};
    int isChange = 1;
    void change_board(vector<vector<char>> &board){
        for(size_t i = 0; i < v.size(); ++i){
                int x = v[i].first;
                int y = v[i].second;
                board[x][y] = 'X';
        }
    }
    void surroundedRegions(vector<vector<char>> &board) {
        // write your code here
        memset(flag, 0, sizeof(flag));
        for(size_t i = 0; i < board.size(); ++i){
                for(size_t j = 0; j < board[i].size(); ++j){
                        if(flag[i][j] == 0 && board[i][j] == 'O'){
                                v.push_back(make_pair(i,j));
                                bfs(i,j, board);
                                if(isChange == 1){
                                        //printf("change:%d %d
",i,j);
                                        change_board(board);
                                }
                                v.clear();
                                isChange = 1;
                        }
                }
        }
    }
    void bfs(int x, int y, vector<vector<char>> board){
        queue<pair<int, int>> que;
        que.push(make_pair(x,y));
        flag[x][y] = 1;
        while(!que.empty()){
                pair<int, int> p = que.front();
                que.pop();



                int nx = 0, ny = 0;
                for(int i = 0; i < 4; ++i){
                        nx = p.first + dir[i][0];
                        ny = p.second + dir[i][1];
                        if(nx >= 0 && nx < board.size() && ny >= 0 && ny < board[0].size()){
                                if(flag[nx][ny] == 0 && board[nx][ny] == 'O'){
                                        v.push_back(make_pair(nx, ny));
                                        que.push(make_pair(nx, ny));
                                        flag[nx][ny] = 1;
                                }
                        } else {
                               // printf("dsad:%d %d
",nx, ny);
                                isChange = 0;
                        }

                }
        }
    }
};

dfs会爆栈 可以 bfs或者用栈模拟函数