poj2752

http://poj.org/problem?id=2752

View Code

   
     

    
      //
    
      寻找前子串与后子串相等的子串
    
      

    
      #include
    
      <
    
      iostream
    
      >
    
      

    
      using
    
       
    
      namespace
    
       std;

    
      char
    
       ch[
    
      400001
    
      ];

    
      int
    
       next[
    
      400001
    
      ];

    
      int
    
       ans[
    
      400001
    
      ];


    
      void
    
       solve (
    
      char
    
       
    
      *
    
      s, 
    
      int
    
       ls)
{
 
    
      int
    
       i
    
      =
    
      0
    
      ,j
    
      =-
    
      1
    
      ;
 next[
    
      0
    
      ] 
    
      =
    
       
    
      -
    
      1
    
      ;
 
    
      while
    
      (i
    
      <
    
      ls)
 {
 
    
      if
    
      (j
    
      ==-
    
      1
    
       
    
      ||
    
       s[i]
    
      ==
    
      s[j])
 {
 i
    
      ++
    
      ;
 j
    
      ++
    
      ;
 next[i] 
    
      =
    
       j;
 }
 
    
      else
    
      
 {
 j 
    
      =
    
       next[j];
 }
 }
}

    
      int
    
       main()
{
 
    
      while
    
      (cin
    
      >>
    
      ch)
 {
 memset(ans , 
    
      0
    
       ,
    
      sizeof
    
      (ans));
 
    
      int
    
       i,j;
 ans[
    
      0
    
      ]
    
      =
    
      strlen(ch);
 i
    
      =
    
      0
    
      ;j
    
      =
    
      1
    
      ;
 solve(ch, ans[
    
      0
    
      ]);
 
 
    
      while
    
      (ans[i
    
      ++
    
      ])
 {
 ans[i] 
    
      =
    
       next[ans[i
    
      -
    
      1
    
      ]];
    
      //
    
      从长到短，递归查找前子串和后子串相等的子串
    
      

    
       }
 
    
      for
    
      (j
    
      =
    
      i
    
      -
    
      2
    
      ;j
    
      >=
    
      0
    
      ;j
    
      --
    
      )
 {
 cout
    
      <<
    
      ans[j]; 
 
    
      if
    
      (j) cout
    
      <<
    
      "
    
       
    
      "
    
      ; 
 } 
 cout
    
      <<
    
      endl;
 } 
 
    
      return
    
       
    
      0
    
      ; 
}