diff --git a/1568. Minimum Number of Days to Disconnect Island b/1568. Minimum Number of Days to Disconnect Island new file mode 100644 index 0000000..59c72ca --- /dev/null +++ b/1568. Minimum Number of Days to Disconnect Island @@ -0,0 +1,86 @@ +class Solution { +public: + int minDays(vector>& grid) { + if (isDisconnected(grid)) return 0; + + int m = grid.size(); + int n = grid[0].size(); + + // Try removing one cell + for (int i = 0; i < m; ++i) { + for (int j = 0; j < n; ++j) { + if (grid[i][j] == 1) { + grid[i][j] = 0; + if (isDisconnected(grid)) return 1; + grid[i][j] = 1; + } + } + } + + // Try removing two cells + for (int i = 0; i < m; ++i) { + for (int j = 0; j < n; ++j) { + if (grid[i][j] == 1) { + grid[i][j] = 0; + for (int x = 0; x < m; ++x) { + for (int y = 0; y < n; ++y) { + if (grid[x][y] == 1) { + grid[x][y] = 0; + if (isDisconnected(grid)) return 2; + grid[x][y] = 1; + } + } + } + grid[i][j] = 1; + } + } + } + return 2; + } + +private: + bool isDisconnected(vector>& grid) { + int m = grid.size(); + int n = grid[0].size(); + vector> visited(m, vector(n, 0)); + + int landCount = 0; + for (int i = 0; i < m; ++i) { + for (int j = 0; j < n; ++j) { + if (grid[i][j] == 1) { + ++landCount; + if (!visited[i][j]) { + if (landCount > 1) return true; + bfs(grid, visited, i, j); + } + } + } + } + return landCount == 0; + } + + void bfs(vector>& grid, vector>& visited, int i, int j) { + int m = grid.size(); + int n = grid[0].size(); + queue> q; + q.push({i, j}); + visited[i][j] = 1; + + vector dirX = {-1, 1, 0, 0}; + vector dirY = {0, 0, -1, 1}; + + while (!q.empty()) { + auto [x, y] = q.front(); + q.pop(); + + for (int d = 0; d < 4; ++d) { + int newX = x + dirX[d]; + int newY = y + dirY[d]; + if (newX >= 0 && newX < m && newY >= 0 && newY < n && grid[newX][newY] == 1 && !visited[newX][newY]) { + visited[newX][newY] = 1; + q.push({newX, newY}); + } + } + } + } +};