LeetCode Problem : Surrounded Regions

Problem

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

A region is captured by flipping all 'O's into 'X's in that surrounded region .

For example,
X X X X
X O O X
X X O X
X O X X
After running your function, the board should be:

X X X X
X X X X
X X X X
X O X X

Code

void solve(vector<vector<char>> &board) {
    // Note: The Solution object is instantiated only once and is reused by each test case.
    int m = board.size();
    if(m == 0)
        return;
    int n = board[0].size();
    vector<vector<bool> > M(m,vector<bool>(n,true));
    for(int j = 0;j < n; ++j){
        M[0][j] = (board[0][j] == 'X');
        M[m - 1][j] = (board[m - 1][j] == 'X');
    }
    for(int i = 1;i < m - 1; ++i){
        M[i][0] = (board[i][0] == 'X');
        M[i][n - 1] = (board[i][n - 1] == 'X');
    }
    bool falseFound = true;
    while(falseFound){
        falseFound = false;
        for(int i = 1;i < m - 1; ++i){
            for(int j = 1;j < n - 1; ++j){
                if(board[i][j] == 'O' && M[i][j]){
                    if(!(M[i][j - 1] && M[i - 1][j])){
                        M[i][j] = false;
                        falseFound = true;
                    }
                }
            }
        }
        for(int i = m - 2;i > 0; --i){
            for(int j = n - 2;j > 0; --j){
                if(board[i][j] == 'O' && M[i][j]){
                    if(!(M[i][j + 1] && M[i + 1][j])){
                        M[i][j] = false;
                        falseFound = true;
                    }
                }
            }
        }
    }
    for(int i = 0;i < m ; ++i){
        for(int j = 0;j < n ; ++j){
            if(M[i][j])
            board[i][j] = 'X';
            else
            board[i][j] = 'O';
        }
    }
}