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| class Solution {
public:
int maxAreaOfIsland(vector<vector<int>>& grid) {
if (grid.empty() || grid[0].empty()) return 0;
int dc[] = {0, 0, -1, 1}, dr[] = {-1, 1, 0, 0};
int n = grid.size(), m = grid[0].size();
int res = 0;
for (int r = 0; r < n; ++r) {
for (int c = 0; c < m; ++c) {
res = max(res, bfs(grid, r, c, dr, dc, n, m));
}
}
return res;
}
int bfs(vector<vector<int>> &grid, int r, int c, int dr[], int dc[], int n, int m) {
queue<pair<int, int>> q;
q.emplace(r, c);
int res = 0;
while (!q.empty()) {
auto [r, c] = q.front(); q.pop();
if (0 <= r && r < n && 0 <= c && c < m && grid[r][c]) {
++res;
grid[r][c] = 0;
for (int i = 0; i < 4; ++i) {
q.emplace(r + dr[i], c + dc[i]);
}
}
}
return res;
}
};
|