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
abhibrat:
20190522 15:04:56
I am getting WA even after using bfs but can't figure out what test case is causing it. Can someone please look at my code https://ideone.com/GHnEOU 

scolar_fuad:
20190403 21:10:24
AC in one shot do not use DFS algo if you want to escape TLE just bfs traversal is quite enough for this problem 

pavanjupalli:
20190113 17:19:43
when i solve using bfs,it gets tle


unknown_user:
20190108 20:48:37
learned multisource bfs


anshumanc007:
20181212 12:50:46
no need to confuse with multisource bfs just store all the indices of '1' in queue and then apply BFS 

masterchef2209:
20181202 17:09:08
AC in 1 go :D


manishjoshi394:
20181107 08:48:08
Do a Multisource bfs from white pixels, it works like a charm! 

harry_shit:
20181102 14:12:11
why tle for bfs?? 

devninja8:
20181017 08:21:13
DO NOT LISTEN TO OTHERS WHILE SOLVING PROBLEM....everyone was saying multisource bfs and i feared cause i have not even heard of that .............i applied simple bfs approach and it got accepted...so ddont listen to anyone else and keep solving your problem....hAPPY Coding!! 

sachinspoj:
20181008 02:36:48
Use multisource bfs :)

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 