diff --git a/src/Search.java b/src/Search.java index cebb278..0aacaba 100644 --- a/src/Search.java +++ b/src/Search.java @@ -1,3 +1,8 @@ +import java.util.ArrayList; +import java.util.LinkedList; +import java.util.List; +import java.util.Queue; + public class Search { /** * Finds the location of the nearest reachable cheese from the rat's position. @@ -29,6 +34,87 @@ public class Search { * @throws HungryRatException if there is no reachable cheese */ public static int[] nearestCheese(char[][] maze) throws EscapedRatException, CrowdedMazeException, HungryRatException { - return null; + boolean[][] visited = new boolean[maze.length][maze[0].length]; + int[] start = ratLocation(maze); + + Queue queue = new LinkedList<>(); + queue.add(start); + + while(!queue.isEmpty()) { + int[] current = queue.poll(); + int currR = current[0]; + int currC = current[1]; + + if(visited[currR][currC]) { + continue; + } + + visited[currR][currC] = true; + if(maze[currR][currC] == 'c') { + return current; + } + + // for(int[] neighbor : getNeighbors(maze, current)) { + // queue.add(neighbor); + // } + queue.addAll(getNeighbors(maze, current)); + } + + throw new HungryRatException(); + } + + public static List getNeighbors(char[][] maze, int[] current) { + int currR = current[0]; + int currC = current[1]; + + int[][] directions = { + {-1, 0}, + {1, 0}, + {0, -1}, + {0, 1} + }; + // Up [-1, 0] + // Down [1, 0] + // Left [0, -1] + // Right [0, 1] + + List possibleMoves = new ArrayList<>(); + + for(int[] direction : directions) { + int changeR = direction[0]; + int changeC = direction[1]; + + int newR = currR + changeR; + int newC = currC + changeC; + + if(newR >= 0 && newR < maze.length && + newC >= 0 && newC < maze[newR].length && + maze[newR][newC] != 'w') { + int[] validMove = {newR, newC}; + possibleMoves.add(validMove); + } + } + + return possibleMoves; + } + + public static int[] ratLocation(char[][] maze) throws EscapedRatException, CrowdedMazeException { + int[] location = null; + + for(int r = 0; r < maze.length; r++) { + for(int c = 0; c < maze[r].length; c++) { + if(maze[r][c] == 'R') { + if(location != null) { + throw new CrowdedMazeException(); + } + location = new int[]{r,c}; + } + } + } + + if(location == null) { + throw new EscapedRatException(); + } + return location; } } \ No newline at end of file