題目鏈接
https://leetcode.com/problems/surrounded-regions/
代碼
int dir[4][2] = {
{0, 1},
{0, -1},
{1, 0},
{-1, 0}
};
class Solution {
public:
void solve(vector<vector<char>>& board) {
if (board.size() == 0) {
return;
}
int row = board.size() - 1, col = board[0].size() - 1;
for (int i = 0; i <= row; ++i) {
if (board[i][0] == 'O') {
dfs(board, i, 0, row, col);
}
if (board[i][col] == 'O') {
dfs(board, i, col, row, col);
}
}
for (int i = 0; i <= col; ++i) {
if (board[0][i] == 'O') {
dfs(board, 0, i, row, col);
}
if (board[row][i] == 'O') {
dfs(board, row, i, row, col);
}
}
for (int i = 0; i <= row; ++i) {
for (int j = 0; j <= col; ++j) {
if (board[i][j] == 'O') {
board[i][j] = 'X';
} else if (board[i][j] == 'S') {
board[i][j] = 'O';
}
}
}
}
void dfs(vector<vector<char>>& board, int i, int j, int row, int col) {
board[i][j] = 'S';
for (int k = 0; k < 4; ++k) {
int ni = dir[k][0] + i, nj = dir[k][1] + j;
if (ni >= 0 && ni <= row && nj >= 0 && nj <= col) {
if (board[ni][nj] == 'O') {
dfs(board, ni, nj, row, col);
}
}
}
}
};
