Sphere Online Judge

SPOJ Problem Set (classical)

206. Bitmap

Problem code: 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 i-th line and j-th column is called the pixel (i,j). The distance between two pixels p1=(i1,j1) and p2=(i2,j2) is defined as:



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.


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 zero-one word of length m, the description of one line of the bitmap, is written. On the j-th position in the line (i+1), 1 <= i <= n, 1 <= j <= m, is '1' if, and only if the pixel (i,j) is white.


In the i-th 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.


Sample input:
3 4

Sample output:
3 2 1 0
2 1 0 0
1 0 0 1

Added by:Piotr Łowiec
Time limit:4s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel Pentium G860 3GHz)
Languages:All except: SCM chicken
Resource:6th Polish Olympiad in Informatics, stage 2

hide comments
2015-01-27 13:10:35 scyther
you just need one word to understand the ques: minesweeper

Last edit: 2015-01-27 13:12:46
2015-01-24 17:48:08 the_imp
getting sigxfsz runtime error .....somebody plz help
--edit(Francky)--> Please see the notes below.
1. Don't post any source code here.
sorry about that but can u help me as to why i might be getting that error...

Last edit: 2015-01-24 20:02:01
2015-01-22 17:54:01 Arafat dad Khan
A brilliant problem with a brilliant solution--- Absolutely loved it
2015-01-22 13:42:27 Rajat (1307086)
Exactly @ Master_Card
2015-01-02 14:14:34 Francky
Is anybody have old Pyramid best timings ? I don't remember my own best time. I think there were several near 0.01s too with Pyramid.
2015-01-02 09:55:26 Kishlay Raj
hw can one solve this in 0.0 , _/\_
2014-10-10 12:21:53 Master_Card
Very good question!!
2013-03-26 10:12:34 Jagatheesvaran Palanisamy
Each of these n lines has length m and contains 0 and/or 1's.

Last edit: 2014-08-18 18:08:57
2013-02-22 22:00:32 reggaeguitar
Can someone please make this sentence more comprehensible "In each of the following n lines of the test case exactly one zero-one word of length m, the description of one line of the bitmap, is written"

Last edit: 2013-02-22 22:00:50
2009-07-08 17:18:11 Ricardo Oliveira [UFPR]
Should I print a blank line between differents test cases in the output?

Edit by Blue Mary: To most SPOJ problems, it doesn't matter :)

Last edit: 2009-07-09 02:48:41
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