Given a 2D array representing the coordinates on the map, there are only values 0, 1, 2 on the map. value 0 means that it can pass, value 1 means not passable, value 2 means target place. Starting from the coordinates [0,0],You can only go up, down, left and right. Find the shortest path that can reach the destination, and return the length of the path.
Example
Example 1
Input:
[
[0, 0, 0],
[0, 0, 1],
[0, 0, 2]
]
Output: 4
Explanation: [0,0] -> [1,0] -> [2,0] -> [2,1] -> [2,2]
Example 2
Input: [ [0,1], [0,1], [0,0], [0,2] ] Output: 4 Explanation: [0,0] -> [1,0] -> [2,0] -> [3,0] -> [3,1]
public class Solution { /** * @param targetMap: * @return: nothing */ public int shortestPath(int[][] targetMap) { // Write your code here Queue<Cell> queue = new LinkedList<>(); int row = targetMap.length, col = targetMap[0].length; boolean[][] visited = new boolean[row][col]; int[][] directions = new int[][]{{-1, 0}, {1, 0}, {0, -1}, {0, 1}}; int res = 0; queue.offer(new Cell(0, 0, targetMap[0][0])); visited[0][0] = true; while(!queue.isEmpty()) { int size = queue.size(); for (int i = 0; i < size; i++) { Cell cur = queue.poll(); if (cur.value == 2) { return res; } for (int[] direction: directions) { int nextRow = cur.row + direction[0]; int nextCol = cur.col + direction[1]; if (isValid(nextRow, nextCol, visited, targetMap)) { queue.offer(new Cell(nextRow, nextCol, targetMap[nextRow][nextCol])); visited[nextRow][nextCol] = true; } } } res += 1; } return -1; } private boolean isValid(int nextRow, int nextCol, boolean[][] visited, int[][] targetMap) { int row = targetMap.length, col = targetMap[0].length; if (nextRow < 0 || nextRow >= row || nextCol < 0 || nextCol >= col || visited[nextRow][nextCol]) { return false; } return targetMap[nextRow][nextCol] != 1; } } class Cell { int row; int col; int value; public Cell(int row, int col, int value) { this.row = row; this.col = col; this.value = value; } }