Navigational Q4s

Navigation Q4s — the hardest variant: walk from a cell according to a rule.

"From (row, col), repeatedly move to the adjacent cell with the smallest value (ties: up, left, right, down); stop when no neighbor is smaller; return the number of moves."

public int descent(int[][] grid, int row, int col) {
    int moves = 0;
    int[][] dirs = { {-1, 0}, {0, -1}, {0, 1}, {1, 0} };
    while (true) {
        int best = grid[row][col];
        int br = -1, bc = -1;
        for (int[] d : dirs) {
            int nr = row + d[0], nc = col + d[1];
            if (nr >= 0 && nr < grid.length && nc >= 0 && nc < grid[0].length) {
                if (grid[nr][nc] < best) {
                    best = grid[nr][nc];
                    br = nr;
                    bc = nc;
                }
            }
        }
        if (br == -1) { return moves; }
        row = br; col = bc; moves++;
    }
}

Reading it: candidate-collection (four guarded reads), a seeded min, and a sentinel stop. Note the tie rule encoded by the DIRECTION ORDER: scanning up→left→right→down with strict < keeps the FIRST preferred direction on ties — the ordering is part of the specification.

Grid walks also test termination: a move rule that can revisit cells needs a visited guard or a step cap (the CP8 path pattern) — check the prompt for which it wants.