2018 acm_icpc 青岛 C题

Flippy Sequence

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Time Limit: 1 Second      Memory Limit: 65536 KB

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DreamGrid has just found two binary sequences  and  ( for all ) from his virtual machine! He would like to perform the operation described below exactly twice, so that  holds for all  after the two operations.

The operation is: Select two integers  and  (), change  to  for all .

DreamGrid would like to know the number of ways to do so.

We use the following rules to determine whether two ways are different:

• Let , where , be a valid operation pair denoting that DreamGrid selects integers  and  for the first operation and integers and  for the second operation;
• Let , where , be another valid operation pair denoting that DreamGrid selects integers  and  for the first operation and integers  and  for the second operation.
•  and  are considered different, if there exists an integer  () such that .

Input

There are multiple test cases. The first line of the input contains an integer , indicating the number of test cases. For each test case:

The first line contains an integer  (), indicating the length of two binary sequences.

The second line contains a string  () of length , indicating the first binary sequence.

The third line contains a string  () of length , indicating the second binary sequence.

It's guaranteed that the sum of  in all test cases will not exceed .

Output

For each test case, output an integer denoting the answer.

Sample Input

3
1
1
0
2
00
11
5
01010
00111

Sample Output

0
2
6

Hint

For the second sample test case, there are two valid operation pairs: (1, 1, 2, 2) and (2, 2, 1, 1).

For the third sample test case, there are six valid operation pairs: (2, 3, 5, 5), (5, 5, 2, 3), (2, 5, 4, 4), (4, 4, 2, 5), (2, 4, 4, 5) and (4, 5, 2, 4).

http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemId=5817

#include 
using namespace std;
char a[1000010],b[1000010];
int main(){
	int n,t;
	scanf("%d",&t);
	while(t--){
		scanf("%d",&n);
		scanf("%s %s",a,b);
		int sum=0;//不同的区间数 
		int w1=0;
		int ww=0;//有两个区间不同时，记录中间相同的个数 
		int x1=0,y1=0; 
		for(int i=0;i