HNU Joke with permutation （深搜dfs）

题目链接：http://acm.hnu.cn/online/?action=problem&type=show&id=13341&courseid=0

Joke with permutation

Time Limit: 3000ms, Special Time Limit:7500ms, Memory Limit:65536KB

Total submit users: 85, Accepted users: 57

Problem 13341 : Special judge

Problem description

Joey had saved a permutation of integers from 1 to n in a text file. All the numbers were written as decimal numbers without leading spaces.

Then Joe
made a practical joke on her: he removed all the spaces in the file.

Help
Joey to restore the original permutation after the Joe’s joke!

Input

The input file contains a single line with a single string — the Joey’s
permutation without spaces.

The Joey’s permutation had at least 1 and at
most 50 numbers.

Output

Write a line to the output file with the restored permutation. Don’t forget
the spaces!

If there are several possible original permutations, write
any one of them.

Sample Input

4111109876532

Sample Output

4 1 11 10 9 8 7 6 5 3 2

Problem Source

NEERC 2014

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题目大意：将一串完整的字符串分成1~n个数。将空格补进去，并将其输出。

解题思路：1、注意这个n是可以求出来的

　　　　　2、一个数字一个数字比较，只要满足这个数字小于n，还有保证这个数字没有访问过就ok啦

　　　

详见代码。

 #include <iostream>
 #include <cstdio>
 #include <cstring>

 using namespace std;

 int n,flag;
 char ch[];
 int ans[];
 bool vis[];

 bool dfs(int i,int k)
 {
     if (flag==)
         return true;
     if (k==n+)
     {
         for (int i=;i<k-;i++)
         {
             printf ("%d ",ans[i]);
         }
         printf ("%d\n",ans[k-]);
         flag=;
         return true;
     }
     if (ch[i]-''<=n&&!vis[ch[i]-'']&&ch[i]-''>)
     {
         ans[k]=ch[i]-'';
         vis[ch[i]-'']=;
         if(dfs(i+,k+)) return true;
         vis[ch[i]-'']=;
     }
     if ((ch[i]-'')*+ch[i+]-''<=n&&(ch[i]-'')*+ch[i+]-''>&&!vis[(ch[i]-'')*+ch[i+]-''])
     {
         ans[k]=(ch[i]-'')*+ch[i+]-'';
         vis[(ch[i]-'')*+ch[i+]-'']=;
         if(dfs(i+,k+)) return true;
         vis[(ch[i]-'')*+ch[i+]-'']=;
     }
     return false;
 }

 int main()
 {
     while (scanf("%s",ch)!=EOF)
     {
         flag=;
         memset(ans,,sizeof(ans));
         memset(vis,,sizeof(vis));
         int len=strlen(ch);
         if (len>)
             n=(len-)/+;
         else
             n=len;
         dfs(,);//dfs();
     }
     return ;
 }