Java/src/test/java/com/thealgorithms/backtracking/MazeRecursionTest.java at c85fdb221848457f4c01f3c535abd08ee1d1fb79 · TheAlgorithms/Java · GitHub

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package com.thealgorithms.backtracking;

import static org.junit.jupiter.api.Assertions.assertArrayEquals;
import static org.junit.jupiter.api.Assertions.assertNull;
import static org.junit.jupiter.api.Assertions.assertSame;
import static org.junit.jupiter.api.Assertions.assertThrows;

import org.junit.jupiter.api.Test;

/**
 * @author onglipwei
 * @create 2022-08-03 5:17 AM
 */
public class MazeRecursionTest {

    @Test
    public void testSmallMazeWithExplicitCoordinates() {
        int[][] firstStrategyMaze = {{0, 0}, {0, 0}};
        int[][] secondStrategyMaze = {{0, 0}, {0, 0}};

        assertArrayEquals(new int[][] {{2, 0}, {2, 2}}, MazeRecursion.solveMazeUsingFirstStrategy(firstStrategyMaze, 0, 0, 1, 1));
        assertArrayEquals(new int[][] {{2, 2}, {0, 2}}, MazeRecursion.solveMazeUsingSecondStrategy(secondStrategyMaze, 0, 0, 1, 1));
    }

    @Test
    public void testLegacyMethodsReturnNullWhenFixedGoalIsOutsideMaze() {
        assertNull(MazeRecursion.solveMazeUsingFirstStrategy(new int[1][1]));
        assertNull(MazeRecursion.solveMazeUsingSecondStrategy(new int[1][1]));
        assertNull(MazeRecursion.solveMazeUsingFirstStrategy(new int[2][2]));
        assertNull(MazeRecursion.solveMazeUsingSecondStrategy(new int[2][2]));
    }

    @Test
    public void testLegacyMethodsReturnNullWhenFixedGoalRowOrColumnIsOutsideMaze() {
        assertNull(MazeRecursion.solveMazeUsingFirstStrategy(new int[7][5]));
        assertNull(MazeRecursion.solveMazeUsingSecondStrategy(new int[6][6]));
    }

    @Test
    public void testLegacyMethodsReturnNullWhenNoPathExists() {
        int[][] firstStrategyMaze = new int[7][6];
        int[][] secondStrategyMaze = new int[7][6];
        firstStrategyMaze[1][1] = 1;
        secondStrategyMaze[1][1] = 1;

        assertNull(MazeRecursion.solveMazeUsingFirstStrategy(firstStrategyMaze));
        assertNull(MazeRecursion.solveMazeUsingSecondStrategy(secondStrategyMaze));
    }

    @Test
    public void testLegacyMethodsAcceptAlreadyMarkedGoal() {
        int[][] firstStrategyMaze = new int[7][6];
        int[][] secondStrategyMaze = new int[7][6];
        firstStrategyMaze[6][5] = 2;
        secondStrategyMaze[6][5] = 2;

        assertSame(firstStrategyMaze, MazeRecursion.solveMazeUsingFirstStrategy(firstStrategyMaze));
        assertSame(secondStrategyMaze, MazeRecursion.solveMazeUsingSecondStrategy(secondStrategyMaze));
    }

    @Test
    public void testNoPathExistsWithExplicitCoordinates() {
        int[][] maze = {{0, 1}, {1, 0}};

        assertNull(MazeRecursion.solveMazeUsingFirstStrategy(maze, 0, 0, 1, 1));
    }

    @Test
    public void testExplicitCoordinatesMustBeInsideMaze() {
        assertThrows(IllegalArgumentException.class, () -> MazeRecursion.solveMazeUsingFirstStrategy(new int[2][2], 0, 0, 2, 1));
    }

    @Test
    public void testEachStartAndGoalCoordinateMustBeInsideMaze() {
        int[][] maze = new int[2][2];

        assertThrows(IllegalArgumentException.class, () -> MazeRecursion.solveMazeUsingFirstStrategy(maze, -1, 0, 1, 1));
        assertThrows(IllegalArgumentException.class, () -> MazeRecursion.solveMazeUsingFirstStrategy(maze, 2, 0, 1, 1));
        assertThrows(IllegalArgumentException.class, () -> MazeRecursion.solveMazeUsingFirstStrategy(maze, 0, -1, 1, 1));
        assertThrows(IllegalArgumentException.class, () -> MazeRecursion.solveMazeUsingFirstStrategy(maze, 0, 2, 1, 1));
        assertThrows(IllegalArgumentException.class, () -> MazeRecursion.solveMazeUsingFirstStrategy(maze, 0, 0, -1, 1));
        assertThrows(IllegalArgumentException.class, () -> MazeRecursion.solveMazeUsingFirstStrategy(maze, 0, 0, 2, 1));
        assertThrows(IllegalArgumentException.class, () -> MazeRecursion.solveMazeUsingFirstStrategy(maze, 0, 0, 1, -1));
        assertThrows(IllegalArgumentException.class, () -> MazeRecursion.solveMazeUsingFirstStrategy(maze, 0, 0, 1, 2));
    }

    @Test
    public void testMazeMustNotBeNullOrEmpty() {
        assertThrows(IllegalArgumentException.class, () -> MazeRecursion.solveMazeUsingFirstStrategy(null));
        assertThrows(IllegalArgumentException.class, () -> MazeRecursion.solveMazeUsingFirstStrategy(new int[0][0]));
        assertThrows(IllegalArgumentException.class, () -> MazeRecursion.solveMazeUsingFirstStrategy(new int[][] {null}));
        assertThrows(IllegalArgumentException.class, () -> MazeRecursion.solveMazeUsingFirstStrategy(new int[][] {new int[0]}));
    }

    @Test
    public void testMazeMustBeRectangular() {
        assertThrows(IllegalArgumentException.class, () -> MazeRecursion.solveMazeUsingFirstStrategy(new int[][] {{0, 0}, {0}}, 0, 0, 1, 0));
    }

    @Test
    public void testBlockedStartAndGoalHaveNoSolution() {
        assertNull(MazeRecursion.solveMazeUsingFirstStrategy(new int[][] {{1, 0}, {0, 0}}, 0, 0, 1, 1));
        assertNull(MazeRecursion.solveMazeUsingSecondStrategy(new int[][] {{0, 0}, {0, 1}}, 0, 0, 1, 1));
    }

    @Test
    public void testOpenSingleCellMazeIsAlreadySolved() {
        assertArrayEquals(new int[][] {{2}}, MazeRecursion.solveMazeUsingFirstStrategy(new int[][] {{0}}, 0, 0, 0, 0));
        assertArrayEquals(new int[][] {{2}}, MazeRecursion.solveMazeUsingSecondStrategy(new int[][] {{0}}, 0, 0, 0, 0));
    }

    @Test
    public void testSolveMazeUsingFirstAndSecondStrategy() {
        int[][] map = new int[8][7];
        int[][] map2 = new int[8][7];

        // We use 1 to indicate walls
        // Set the ceiling and floor to 1
        for (int i = 0; i < 7; i++) {
            map[0][i] = 1;
            map[7][i] = 1;
        }
        // Set the left and right wall to 1
        for (int i = 0; i < 8; i++) {
            map[i][0] = 1;
            map[i][6] = 1;
        }
        // Set obstacles
        map[3][1] = 1;
        map[3][2] = 1;

        // Clone the original map for the second pathfinding strategy
        for (int i = 0; i < map.length; i++) {
            System.arraycopy(map[i], 0, map2[i], 0, map[i].length);
        }

        // Solve the maze using the first strategy
        int[][] solvedMap1 = MazeRecursion.solveMazeUsingFirstStrategy(map);
        // Solve the maze using the second strategy
        int[][] solvedMap2 = MazeRecursion.solveMazeUsingSecondStrategy(map2);
        int[][] expectedMap1 = new int[][] {
            {1, 1, 1, 1, 1, 1, 1},
            {1, 2, 0, 0, 0, 0, 1},
            {1, 2, 2, 2, 0, 0, 1},
            {1, 1, 1, 2, 0, 0, 1},
            {1, 0, 0, 2, 0, 0, 1},
            {1, 0, 0, 2, 0, 0, 1},
            {1, 0, 0, 2, 2, 2, 1},
            {1, 1, 1, 1, 1, 1, 1},
        };
        int[][] expectedMap2 = new int[][] {
            {1, 1, 1, 1, 1, 1, 1},
            {1, 2, 2, 2, 2, 2, 1},
            {1, 0, 0, 0, 0, 2, 1},
            {1, 1, 1, 0, 0, 2, 1},
            {1, 0, 0, 0, 0, 2, 1},
            {1, 0, 0, 0, 0, 2, 1},
            {1, 0, 0, 0, 0, 2, 1},
            {1, 1, 1, 1, 1, 1, 1},
        };

        // Assert the results
        assertArrayEquals(expectedMap1, solvedMap1);
        assertArrayEquals(expectedMap2, solvedMap2);
    }
}