Package g0901_1000.s0980_unique_paths_iii

Class Solution

java.lang.Object

g0901_1000.s0980_unique_paths_iii.Solution

public class Solution
extends Object

980 - Unique Paths III\. Hard You are given an `m x n` integer array `grid` where `grid[i][j]` could be: * `1` representing the starting square. There is exactly one starting square. * `2` representing the ending square. There is exactly one ending square. * `0` representing empty squares we can walk over. * `-1` representing obstacles that we cannot walk over. Return _the number of 4-directional walks from the starting square to the ending square, that walk over every non-obstacle square exactly once_. **Example 1:**  **Input:** grid = \[\[1,0,0,0],[0,0,0,0],[0,0,2,-1]] **Output:** 2 **Explanation:** We have the following two paths: 1. (0,0),(0,1),(0,2),(0,3),(1,3),(1,2),(1,1),(1,0),(2,0),(2,1),(2,2) 2. (0,0),(1,0),(2,0),(2,1),(1,1),(0,1),(0,2),(0,3),(1,3),(1,2),(2,2) **Example 2:**  **Input:** grid = \[\[1,0,0,0],[0,0,0,0],[0,0,0,2]] **Output:** 4 **Explanation:** We have the following four paths: 1. (0,0),(0,1),(0,2),(0,3),(1,3),(1,2),(1,1),(1,0),(2,0),(2,1),(2,2),(2,3) 2. (0,0),(0,1),(1,1),(1,0),(2,0),(2,1),(2,2),(1,2),(0,2),(0,3),(1,3),(2,3) 3. (0,0),(1,0),(2,0),(2,1),(2,2),(1,2),(1,1),(0,1),(0,2),(0,3),(1,3),(2,3) 4. (0,0),(1,0),(2,0),(2,1),(1,1),(0,1),(0,2),(0,3),(1,3),(1,2),(2,2),(2,3) **Example 3:**  **Input:** grid = \[\[0,1],[2,0]] **Output:** 0 **Explanation:** There is no path that walks over every empty square exactly once. Note that the starting and ending square can be anywhere in the grid. **Constraints:** * `m == grid.length` * `n == grid[i].length` * `1 <= m, n <= 20` * `1 <= m * n <= 20` * `-1 <= grid[i][j] <= 2` * There is exactly one starting cell and one ending cell.

Constructor Summary

Constructors

Constructor	Description
Solution()

Method Summary

Modifier and Type	Method	Description
int	uniquePathsIII(int[][] grid)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

Solution

public Solution()

Method Details

uniquePathsIII

public int uniquePathsIII(int[][] grid)