BITMAP  Bitmap
There is given a rectangular bitmap of size n*m. Each pixel of the bitmap is either white or black, but at least one is white. The pixel in ith line and jth column is called the pixel (i,j). The distance between two pixels p_{1}=(i_{1},j_{1}) and p_{2}=(i_{2},j_{2}) is defined as:
Task
Write a program which:
 reads the description of the bitmap from the standard input,
 for each pixel, computes the distance to the nearest white pixel,
 writes the results to the standard output.
Input
The number of test cases t is in the first line of input, then t test cases follow separated by an empty line. In the first line of each test case there is a pair of integer numbers n, m separated by a single space, 1<=n <=182, 1<=m<=182. In each of the following n lines of the test case exactly one zeroone word of length m, the description of one line of the bitmap, is written. On the jth position in the line (i+1), 1 <= i <= n, 1 <= j <= m, is '1' if, and only if the pixel (i,j) is white.
Output
In the ith line for each test case, 1<=i<=n, there should be written m integers f(i,1),...,f(i,m) separated by single spaces, where f(i,j) is the distance from the pixel (i,j) to the nearest white pixel.
Example
Sample input: 1 3 4 0001 0011 0110 Sample output: 3 2 1 0 2 1 0 0 1 0 0 1
hide comments
Aqib Ahmed J:
20160208 14:58:23
Took a while to realize how exactly but AC in one go :) 0.04s !! 

bunnycoder:
20160129 22:09:37
Silly error .....


archit saxena:
20160113 06:48:06
done with bfs using 0.03 sec but people might also try solving equation(try on paper and u will get easy graphical solution) mod(x1x2)+mod(y1y2)=z;and find the minimum value of z using binary search might work.if it works do comment 

dokz:
20160108 14:23:29
Got WA at first, because of input. "then t test cases follow separated by an empty line". Note that there is a new line after every test case. 

utkarsh5:
20151222 11:38:19
Can someone provide me some sample test cases, Im getting wrong answer even though my code produces correct answer for all the test cases Ive built so far? 

sunil:
20151129 11:44:19
wtf nothing is working neither brute force nor bfs


vedang:
20151127 22:40:26
nice beginner level graph problem... 

mdsharique:
20151020 17:47:33
Last edit: 20151027 14:39:10 

Advitiya:
20151020 01:35:16
bfs using queue 0.20 AC! :D 

agspoj:
20150922 08:58:27
I finally solved it. If someone is interested this is the testcase which caused problem: "1\n4 6\n100001\n100001\n100001\n100001". Last edit: 20151013 20:36:44 
Added by:  Piotr Ćowiec 
Date:  20040913 
Time limit:  4s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All 
Resource:  6th Polish Olympiad in Informatics, stage 2 