CLEANRBT  Cleaning Robot
Here, we want to solve path planning for a mobile robot cleaning a rectangular room floor with furniture.
Consider the room floor paved with square tiles whose size fits the cleaning robot (1 × 1). There are 'clean tiles' and 'dirty tiles', and the robot can change a 'dirty tile' to a 'clean tile' by visiting the tile. Also there may be some obstacles (furniture) whose size fits a tile in the room. If there is an obstacle on a tile, the robot cannot visit it. The robot moves to an adjacent tile with one move. The tile onto which the robot moves must be one of four tiles (i.e., east, west, north or south) adjacent to the tile where the robot is present. The robot may visit a tile twice or more.
Your task is to write a program which computes the minimum number of moves for the robot to change all 'dirty tiles' to 'clean tiles', if ever possible.
Input
IThe input consists of multiple maps, each representing the size and arrangement of the room. A map is given in the following format.
w h
c11 c12 c13 ... c1w
c21 c22 c23 ... c2w
...
ch1 ch2 ch3 ... chw
The integers w and h are the lengths of the two sides of the floor of the room in terms of widths of floor tiles. w and h are less than or equal to 20. The character cyx represents what is initially on the tile with coordinates (x, y) as follows.
'.' : a clean tile
'*' : a dirty tile
'x' : a piece of furniture (obstacle)
'o' : the robot (initial position)
In the map the number of 'dirty tiles' does not exceed 10. There is only one 'robot'.
The end of the input is indicated by a line containing two zeros.
Output
For each map, your program should output a line containing the minimum number of moves. If the map includes 'dirty tiles' which the robot cannot reach, your program should output 1.
Example
Input: 7 5 ....... .o...*. ....... .*...*. ....... 15 13 .......x....... ...o...x....*.. .......x....... .......x....... .......x....... ............... xxxxx.....xxxxx ............... .......x....... .......x....... .......x....... ..*....x....*.. .......x....... 10 10 .......... ..o....... .......... .......... .......... .....xxxxx .....x.... .....x.*.. .....x.... .....x.... 0 0 Output: 8 49 1
hide comments
Archit Jain:
20150218 15:50:36
nice dp 

yousef hadder:
20140316 07:48:07
i changed my 'vist' array from global int into local bool and my time differed by two seconds :\ 

BLANKRK:
20130714 14:01:32
got AC but surly one of my nonregular type code .... :P 

Mukesh Yadav:
20121208 22:25:57
oh , got it Finally , thnx @ :D 

Ahmed Abo El Kheir:
20120922 19:19:12
what DP? Please tell me how you can solve a problem like this by DP because all what i can think about is BFS 

:D:
20120915 10:24:53
By looking at it per permutation your code is being very redundant. There is other, much more efficient DP approach. Maybe try looking at permutations sequences and try to think what can be limited. I will not straight out say how to do it. 

Mukesh Yadav:
20120915 10:19:27
Hey , How Did u get time so close to zero , i did it by finding all pairs shortest path and then checking all the permutations ...... Any Hints to improve this time limit pls ???

Added by:  Camilo Andrés Varela León 
Date:  20070726 
Time limit:  0.609s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ERL JSRHINO NODEJS PERL6 VB.NET 
Resource:  Japan Domestic, 2005 