HDU 1501 Zipper

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=1501

Zipper

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 7439    Accepted Submission(s): 2627

Problem Description

Given three strings, you are to determine whether the third string can be formed by combining the characters in the first two strings. The first two strings can be mixed arbitrarily, but each must stay in its original order.

For example, consider forming "tcraete" from "cat" and "tree":

String A: cat
String B: tree
String C: tcraete


As you can see, we can form the third string by alternating characters from the two strings. As a second example, consider forming "catrtee" from "cat" and "tree":

String A: cat
String B: tree
String C: catrtee


Finally, notice that it is impossible to form "cttaree" from "cat" and "tree".

 

Input

The first line of input contains a single positive integer from 1 through 1000. It represents the number of data sets to follow. The processing for each data set is identical. The data sets appear on the following lines, one data set per line.

For each data set, the line of input consists of three strings, separated by a single space. All strings are composed of upper and lower case letters only. The length of the third string is always the sum of the lengths of the first two strings. The first two strings will have lengths between 1 and 200 characters, inclusive.

 

Output

For each data set, print:

Data set n: yes

if the third string can be formed from the first two, or

Data set n: no

if it cannot. Of course n should be replaced by the data set number. See the sample output below for an example.

 

Sample Input

3cat tree tcraetecat tree catrteecat tree cttaree

 

Sample Output

Data set 1: yesData set 2: yesData set 3: no

题意：问你能否用前两个单词拼出后一个单词，前两个单词每个单词内字母顺序不变。

记得标记下访问过的。具体为什么，自己动脑筋思考下。

下面是AC代码

#include<iostream>using namespace std;string sa,sb,sc;bool vis[205][205],flag;void dfs(int a,int b,int c){    if(c==sc.size())    {        flag=1;        return ;    }    if(flag) return ;    if(vis[a][b]) return ;    vis[a][b]=1;    if(sa[a]==sc[c]) dfs(a+1,b,c+1);    if(flag) return ;    if(sb[b]==sc[c]) dfs(a,b+1,c+1);}int main(){    int t,Case=1;    cin>>t;    while(t--)    {        cin>>sa>>sb>>sc;        fill(&vis[0][0],&vis[205][0],0);        flag=0;        dfs(0,0,0);        cout<<"Data set "<<Case++<<": ";        if(flag) cout<<"yes"<<endl;        else cout<<"no"<<endl;    }    return 0;}