solution_dfs.cpp

// DFS

classSolution {
public:
intnumEnclaves(vector<vector<int>>& g) {
int n = g.size(), m = g[0].size();
int ans = 0;
 vector<int> d{0, 1, 0, -1, 0};
 function<bool(int, int, int &)> dfs = [&](int i, int j, int &cnt) {
if(i < 0 || j < 0 || i >= n || j >= m)
returntrue;
if(g[i][j] == 0)
returnfalse;
 g[i][j] = 0;
 cnt++;
bool flag = false;
for(int k = 0; k < 4; k++)
 flag |= dfs(i + d[k], j + d[k + 1], cnt);
return flag;
 };
for(int i = 0; i < n; i++) {
for(int j = 0; j < m; j++) {
int cnt = 0;
if(!dfs(i, j, cnt))
 ans += cnt;
 }
 }
return ans;
 }
};