lintcode - 被围绕的区域
1 class Solution { 2 public: 3 /* 4 * @param board: board a 2D board containing 'X' and 'O' 5 * @return: nothing 6 */ 7 bool flag[220][220]; 8 vector<pair<int, int>> v; 9 const int dir[4][2] = {{0,1}, {1,0}, {0, -1}, {-1, 0}}; 10 int isChange = 1; 11 void change_board(vector<vector<char>> &board){ 12 for(size_t i = 0; i < v.size(); ++i){ 13 int x = v[i].first; 14 int y = v[i].second; 15 board[x][y] = 'X'; 16 } 17 } 18 void surroundedRegions(vector<vector<char>> &board) { 19 // write your code here 20 memset(flag, 0, sizeof(flag)); 21 for(size_t i = 0; i < board.size(); ++i){ 22 for(size_t j = 0; j < board[i].size(); ++j){ 23 if(flag[i][j] == 0 && board[i][j] == 'O'){ 24 v.push_back(make_pair(i,j)); 25 bfs(i,j, board); 26 if(isChange == 1){ 27 //printf("change:%d %d\n",i,j); 28 change_board(board); 29 } 30 v.clear(); 31 isChange = 1; 32 } 33 } 34 } 35 } 36 void bfs(int x, int y, vector<vector<char>> board){ 37 queue<pair<int, int>> que; 38 que.push(make_pair(x,y)); 39 flag[x][y] = 1; 40 while(!que.empty()){ 41 pair<int, int> p = que.front(); 42 que.pop(); 43 44 45 46 int nx = 0, ny = 0; 47 for(int i = 0; i < 4; ++i){ 48 nx = p.first + dir[i][0]; 49 ny = p.second + dir[i][1]; 50 if(nx >= 0 && nx < board.size() && ny >= 0 && ny < board[0].size()){ 51 if(flag[nx][ny] == 0 && board[nx][ny] == 'O'){ 52 v.push_back(make_pair(nx, ny)); 53 que.push(make_pair(nx, ny)); 54 flag[nx][ny] = 1; 55 } 56 } else { 57 // printf("dsad:%d %d\n",nx, ny); 58 isChange = 0; 59 } 60 61 } 62 } 63 } 64 };
dfs会爆栈 可以 bfs或者用栈模拟函数
