Update shortest_distance_from_all_buildings.md

Author: Joseph Luce

real_interview_questions/Google/shortest_distance_from_all_buildings.md

@@ -1,3 +1,29 @@
+# QUESTION
+You want to build a house on an empty land which reaches all buildings in the shortest amount of distance. You can only move up, down, left and right. You are given a 2D grid of values 0, 1 or 2, where:
+
+Each 0 marks an empty land which you can pass by freely.
+Each 1 marks a building which you cannot pass through.
+Each 2 marks an obstacle which you cannot pass through.
+Example:
+```
+Input: [[1,0,2,0,1],[0,0,0,0,0],[0,0,1,0,0]]
+
+1 - 0 - 2 - 0 - 1
+|   |   |   |   |
+0 - 0 - 0 - 0 - 0
+|   |   |   |   |
+0 - 0 - 1 - 0 - 0
+
+Output: 7 
+
+Explanation: Given three buildings at (0,0), (0,4), (2,2), and an obstacle at (0,2),
+             the point (1,2) is an ideal empty land to build a house, as the total 
+             travel distance of 3+3+1=7 is minimal. So return 7.
+Note:
+There will be at least one building. If it is not possible to build such house according to the above rules, return -1.
+             
+```
+
 # SOLUTION (Time Limit Exceeded)
 ```
 class Solution(object):