import { Grid } from '../Grid';
import { CellValueChange } from '../ValueTypes';
export declare class BacktrackingSolver {
    /**
     * The source of changes provided to callers.
     */
    static source: string;
    /**
     * Completes the grid using a backtracking algorithm but is optimised to only select
     * values that appear in the CelValue potentials. It will always work but is a very inefficient
     * and non-human way to do things. if you're writing a Sudoku puzzle game and want to be able to
     * provide players with hints etc, this method probably isn't the one you'd choose.
     * @param targetGrid The grid to solve.
     * @returns An empty array as Backtracking completes itself.
     */
    static solve(targetGrid: Grid): CellValueChange[];
    /**
     * Performs the backtracking recursion.
     * @param grid A reference to a new copy of the grid (this is why everything is immutable!)
     * @returns A value indicating whether the grid id still valid.
     */
    static doBackTracking(grid: Grid, completed: (grid: Grid) => void, depth?: number): boolean;
    /**
     * Helper method to confirm that a given cell in a grid can have a value.
     * @param grid Grid to check placemnet on.
     * @param value Value to check.
     * @param location Location of cell for proposed value.
     * @returns True if the cell is allowed the specified value.
     */
    private static isValidPlacement;
}