HLAMPS - Lampice

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LAMPICE
2*N light bulbs are arranged in two rows and N columns. Each light bulb can be either off or on, and 
all lights are initially off. 
We want to turn some of them on so that they form a beautiful pattern. In one step we can change 
the state of a sequence of (one or more) consecutive light bulbs in the same row or column. 
Given the desired pattern, write a program that finds the minimum number of steps required to form 
the pattern. 
 
The following figure illustrates the seven steps needed to obtain the pattern given in the third example: 
 

0

00000000000000000000

00000000000000000000

1

11100000000000000000

00000000000000000000

2

11100010000000000000

00000010000000000000

3

11100010000000000000

01111101100000000000

4

11101101111000000000

01111101100000000000

5

11101101111000111110

01111101100000000000

6

11101101111000101110

01111101100000010000

7

11101101111000101010

01111101100000010100

 
input data 
The first line of input contains an integer N, 1 ≤ N ≤ 10,000, the number of columns. 
Each of the following two lines contains a sequence of N characters representing the desired final 
pattern. 
Character '1' indicates a light bulb that should be on in the final state, while the character '0' indicates a 
light bulb that should be off. 
output data 
The first and only line of output should contain a single integer – the minimum number of steps 
required. 
examples 
input 
 
100 
000 
 
output 
 
input 
 
11011 
11011 
 
output 
 
input 
 
20 
11101101111000101010 
01111101100000010100 
 
output 
 

 

 



Added by:DVH
Date:2013-12-12
Time limit:1s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: ASM64
Resource: Croatian Regional Competition in Informatics 2006