Hdu 5151 sit sit sit

http://acm.hdu.edu.cn/showproblem.php?pid=5151

Test instructions: A total of n chairs, and then there are N students to sit in turn, meet the following three conditions can not sit up, 1: The chair next to the left chair also has a right chair, 2: The chair is sitting next to the seat, 3: The chair next to the color of the chair.

Ask if everyone is sitting up and there's a lot of things.

DP[I][J] Indicates the number of conditions that the interval [i,j] satisfies. This problem is an interval DP. A large interval is processed into a number of small intervals.

1#include <cstdio>2#include <cstring>3#include <algorithm>4 #defineMoD 10000000075 #definell Long Long6 using namespacestd;7 8 intN;9 inta[ $];Tenll c[ $][ $]; Onell dp[ $][ $]; A  - voidInti () - { the      for(intI=0; i<=101; i++) -     { -c[i][0]=1; -          for(intj=1; j<=i; J + +) +         { -C[i][j]= (c[i-1][j]+c[i-1][j-1])%MoD; +         } A     } at } -  -ll Get_num (intXinty) - { -     if(x>y)return 0; -     if(Dp[x][y])returnDp[x][y]; in     if(x==y)returndp[x][y]=1; -ll ans=0; to      for(inti=x+1; i<y; i++) +     { -         if(a[i-1]!=a[i+1])Continue; theAns+=get_num (x,i-1) *get_num (i+1, y)%mod*c[y-x][i-x]%MoD; *ans%=MoD; $     }Panax NotoginsengAns+=get_num (x+1, y); -ans%=MoD; theAns+=get_num (x,y-1); +ans%=MoD; Adp[x][y]=ans; the     returnDp[x][y]; + } -  $ intMain () $ { - Inti (); -      while(SCANF ("%d", &n)! =EOF) the     { -Memset (DP,0,sizeof(DP));Wuyi          for(intI=1; i<=n; i++) the         { -scanf"%d",&a[i]); Wu         } -printf"%lld\n", Get_num (1, N)); About     } $     return 0; -}

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Hdu 5151 sit sit sit