Depth-First search Codevs 1065 01 Strings

Codevs 1065 01 Stringtime limit: 1 sspace limit: 128000 KBtitle level: Golden GoldTitle Description Description

The output is only a string of length n of 0 and 1, and it cannot contain 3 contiguous strings of the same substring.

Enter a description Input Description

The input file has only one line of integer n, representing the length of the string consisting of 0 and 1. 0<=n<=30.

Output description Output Description

The output file has only one line of integers, representing the number of strings that satisfy the criteria.

Sample input Sample Input

1

Sample output Sample Output

2

1 /*dfs+ Violence Test2 */3#include <iostream>4 using namespacestd;5#include <cstring>6#include <cstdio>7 Charans[ *];8 intn,sum=0;9 BOOLCheckintL1,intR1,intL2,intR2)Ten { One      while(l1<=r1&&l2<=R2) A     { -         if(Ans[l1]!=ans[l2])return false; -l1++;l2++; the     } -     return true; - } - voidDfsintk) + { -     if(k==n+1) +     { Asum++; at         return; -     } -      for(intI=0; i<=1;++i) -     { -ans[k]=i+'0'; -         BOOLflag=true; in          for(intj=1; j<=k/3;++j) -           if(Check (k-j+1, k,k-j-j+1, k-j) &&check (k-j+1, k,k-j-j-j+1, k-j-j)) to{flag=false; +             Break; -                   } the         if(flag) *         { $DFS (k +1);Panax Notoginsengans[k]=0; -         }       the         Else Continue;  +     } A } the intMain () + { -scanf"%d",&n); $     if(n==0) $     { -printf"0"); -         return 0; the     } -Dfs1);Wuyiprintf"%d\n", sum); the     return 0; -}

Depth-First search Codevs 1065 01 Strings