【hdu】Zipper （dfs）

最新推荐文章于 2021-03-28 21:19:39 发布

Sun.R@in

最新推荐文章于 2021-03-28 21:19:39 发布

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文章标签： string tree each input processing integer

本文链接：https://blog.youkuaiyun.com/zfz1015/article/details/7832806

本文介绍了一个算法问题，探讨如何判断第三字符串是否能由前两个字符串的字符按原顺序组合而成。通过深度优先搜索（DFS）结合访问标记的方法，有效地解决了这一问题，并提供了完整的代码实现。

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Zipper

Time Limit : 2000/1000ms (Java/Other) Memory Limit : 131072/65536K (Java/Other)

Total Submission(s) : 11 Accepted Submission(s) : 5

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

注意visit数组标记，表示已经搜索过，否则超时! (dfs+visit标记 )

#include<cstdio>
#include<cstring>
char str1[210],str2[210],str[410],visit[210][210];
int len1,len2,len,flag;
void dfs(int a,int b,int c)
{
  /*  if(a==len1&&b==len2&&c==len){flag=1;return;}
    if(a>len1||b>len2) return;
    if(str[c]==str1[a])dfs(a+1,b,c+1);
    if(str[c]==str2[b])dfs(a,b+1,c+1);
    if(str[c]!=str1[a]||str[c]!=str2[b])return;
    */
    if(c==len) {flag=1;return;}
    if(flag)return ;
    if(visit[a][b])return;
    visit[a][b]=1;
    if(str[c]==str1[a])dfs(a+1,b,c+1);
    if(str[c]==str2[b])dfs(a,b+1,c+1);
    if(str[c]!=str1[a]||str[c]!=str2[b])return;
    
}
        
int main()
{
   int n,i,j,t=0;
   scanf("%d",&n);
   while(n--)
   {
             getchar();
             t++;
             memset(visit,0,sizeof(visit));
             scanf("%s%s%s",str1,str2,str);
             len1=strlen(str1);
             len2=strlen(str2);
             len=len1+len2;
             flag=0;
             dfs(0,0,0);
             if(flag)printf("Data set %d: yes\n",t);
             else printf("Data set %d: no\n",t);
   }
return 0;
}