1034. Coloring A Border

class Solution {
    private int[][] grid;
    private int color;
    private int m;
    private int n;
    private boolean[][] vis;

    public int[][] colorBorder(int[][] grid, int row, int col, int color) {
        this.grid = grid;
        this.color = color;
        m = grid.length;
        n = grid[0].length;
        vis = new boolean[m][n];
        dfs(row, col, grid[row][col]);
        return grid;
    }

    private void dfs(int i, int j, int c) {
        vis[i][j] = true;
        int[] dirs = {-1, 0, 1, 0, -1};
        for (int k = 0; k < 4; ++k) {
            int x = i + dirs[k], y = j + dirs[k + 1];
            if (x >= 0 && x < m && y >= 0 && y < n) {
                if (!vis[x][y]) {
                    if (grid[x][y] == c) {
                        dfs(x, y, c);
                    } else {
                        grid[i][j] = color;
                    }
                }
            } else {
                grid[i][j] = color;
            }
        }
    }
}