【HDOJ6148】Valley Numer（数位DP）

题意：

1≤T≤200

● 1≤length(N)≤100

思路：

设f[i,j,k,l]为第i位为j，前i位是否贴上限(0/1)，递减或递增(0/1)方案数

g[i,j,k]为不到n位，第i位为j，递减或递增方案数

 const mo=;
 var f:array[..,..,..,..]of longint;
     g:array[..,..,..]of longint;
     a:array[..]of longint;
     v,n,i,j,k,l,jj,kk,ans,cas,ll:longint;
     ch:string;

 begin

  readln(cas);
  for v:= to cas do
  begin
   readln(ch);
   n:=length(ch);
   for i:= to n do a[i]:=;
   for i:= to n do a[i]:=ord(ch[i])-ord('');
   for i:= to n do
    for j:= to  do
     for k:= to  do
      for l:= to  do f[i,j,k,l]:=;
   for i:= to a[]- do f[,i,,]:=;
   f[,a[],,]:=;
   for i:= to n do
    for j:= to  do
     for k:= to  do
      for l:= to  do
       for jj:= to  do
       begin
        if k= then kk:=;
        if (k=)and(jj<a[i]) then kk:=;
        if (k=)and(jj=a[i]) then kk:=;
        if (k=)and(jj>a[i]) then break;
        for ll:=l to  do
        begin
         if (ll=)and(j<jj) then continue;
         if (ll=)and(j>jj) then continue;
         if (ll<>l)and(j=jj) then continue;
         f[i,jj,kk,ll]:=(f[i,jj,kk,ll]+f[i-,j,k,l]) mod mo;
        end;
       end;
   for i:= to n- do
    for j:= to  do
     for k:= to  do g[i,j,k]:=;
   for i:= to  do g[,i,]:=;
   for i:= to n- do
     for j:= to  do
      for k:= to  do
       for jj:= to  do
        for kk:=k to  do
        begin
         if (kk=)and(j<jj) then continue;
         if (kk=)and(j>jj) then continue;
         if (k<>kk)and(j=jj) then continue;
         g[i,jj,kk]:=(g[i,jj,kk]+g[i-,j,k]) mod mo;
        end;
   ans:=;
   for j:= to  do
    for k:= to  do
     for l:= to  do ans:=(ans+f[n,j,k,l]) mod mo;
   for i:= to n- do
    for j:= to  do
     for k:= to  do ans:=(ans+g[i,j,k]) mod mo;
   writeln(ans);
  end;

 end.