LC: 286. Walls and Gates

https://leetcode.com/problems/walls-and-gates/

Question

286. Walls and Gates

You are given an m x n grid rooms initialized with these three possible values.

• -1 A wall or an obstacle.

• 0 A gate.

• INF Infinity means an empty room. We use the value 231 - 1 = 2147483647 to represent INF as you may assume that the distance to a gate is less than 2147483647.

Fill each empty room with the distance to its nearest gate. If it is impossible to reach a gate, it should be filled with INF.

Example 1:

Input: rooms = [[2147483647,-1,0,2147483647],[2147483647,2147483647,2147483647,-1],[2147483647,-1,2147483647,-1],[0,-1,2147483647,2147483647]]
Output: [[3,-1,0,1],[2,2,1,-1],[1,-1,2,-1],[0,-1,3,4]]

Example 2:

Input: rooms = [[-1]]
Output: [[-1]]

Example 3:

Input: rooms = [[2147483647]]
Output: [[2147483647]]

Example 4:

Input: rooms = [[0]]
Output: [[0]]

Constraints:

• m == rooms.length

• n == rooms[i].length

• 1 <= m, n <= 250

• rooms[i][j] is -1, 0, or 231 - 1.

The Essence

Details and Solutions