Give a gird, and there are `X` and `Y` in this grid. find the shortest distance between `X` and `Y`.\n\n**Example 1:** \n```\nInput:\n[[X,0,0],\n [0,Y,0],\n [X,Y,0]] \nOutput: 1\n```\n\n**Example 2:**\n```\nInput:\n[[X,X,0],\n [0,0,Y],\n [Y,0,0]] \nOutput: 2\n```\n\n<details> \n  <summary>Solution</summary>\n\n`Java` Multisource BFS: https://leetcode.com/playground/cbPfw8Zd\nTime complexity: `O(r * c)`.\nSpace complexity: `O(r * c)`.\n</details>\n\n**Follow-up:**\nOutput coordinates of the closet XY pair.

Give a gird, and there are X and Y in this grid. find the shortest distance between X and Y.\n\nExample 1: \n\nInput:\n[[X,0,0],\n [0,Y,0],\n [X,Y,0]] \nOutput:

Google | Phone screen | Closest XY pair in a grid