// Chain of Command // Solution by Jacob Plachta #define DEBUG 0 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; #define LL long long #define LD long double #define PR pair #define Fox(i,n) for (i=0; i=0; i--) #define FoxR1(i,n) for (i=n; i>0; i--) #define FoxRI(i,a,b) for (i=b; i>=a; i--) #define Foxen(i,s) for (i=s.begin(); i!=s.end(); i++) #define Min(a,b) a=min(a,b) #define Max(a,b) a=max(a,b) #define Sz(s) int((s).size()) #define All(s) (s).begin(),(s).end() #define Fill(s,v) memset(s,v,sizeof(s)) #define pb push_back #define mp make_pair #define x first #define y second template T Abs(T x) { return(x<0 ? -x : x); } template T Sqr(T x) { return(x*x); } string plural(string s) { return(Sz(s) && s[Sz(s)-1]=='x' ? s+"en" : s+"s"); } const int INF = (int)1e9; const LD EPS = 1e-12; const LD PI = acos(-1.0); #if DEBUG #define GETCHAR getchar #else #define GETCHAR getchar_unlocked #endif bool Read(int &x) { char c,r=0,n=0; x=0; for(;;) { c=GETCHAR(); if ((c<0) && (!r)) return(0); if ((c=='-') && (!r)) n=1; else if ((c>='0') && (c<='9')) x=x*10+c-'0',r=1; else if (r) break; } if (n) x=-x; return(1); } #define LIM 800001 #define MOD 1000000007 int N; LL curSum; int ind,sz[LIM],in[LIM],out[LIM],nxt[LIM]; int C[LIM],S[LIM]; int BLT[2][LIM]; // 0: B, 1: X bool X[LIM],hasSetXUpward[LIM]; vector ch[LIM],unsetXch[LIM]; void RecCalcSz(int i) { int j; sz[i]=1; Fox(j,Sz(ch[i])) { int c=ch[i][j]; RecCalcSz(c); sz[i]+=sz[c]; if(sz[c]>sz[ch[i][0]]) swap(ch[i][0],ch[i][j]); } } void RecHLD(int i) { in[i]=ind++; int j; Fox(j,Sz(ch[i])) { int c=ch[i][j]; nxt[c]=j ? c : nxt[i]; RecHLD(c); } out[i]=ind; } void IncBLT(int b,int i) { for (i++; i<=N; i+=(i&-i)) BLT[b][i]++; } int QueryBLT(int b,int i) { int s=0; for (i++; i>0; i-=(i&-i)) s+=BLT[b][i]; return(s); } int QueryBInSubtree(int i) { return(QueryBLT(0,out[i]-1)-QueryBLT(0,in[i]-1)); } int QueryXToRoot(int i) { int x=1; while (i>=0) { int a=nxt[i]; x+=QueryBLT(1,in[i])-QueryBLT(1,in[a]-1); i=C[a]; } return(x); } void SetX(int i) { if (X[i]) return; X[i]=1; IncBLT(1,in[i]); curSum+=QueryBInSubtree(i); } void Bribe(int i) { int j; IncBLT(0,in[i]); curSum+=QueryXToRoot(i); Fox(j,Sz(ch[i])) SetX(ch[i][j]); for(;;) { if (hasSetXUpward[i]) break; hasSetXUpward[i]=1; int c=C[i]; if (c<0) break; Fox(j,Sz(unsetXch[c])) if (unsetXch[c][j]!=i) SetX(unsetXch[c][j]); unsetXch[c].clear(); unsetXch[c].pb(i); i=c; } } int main() { if (DEBUG) freopen("in.txt","r",stdin); // vars int T,t; int i,r; // testcase loop Read(T); Fox1(t,T) { // init Fox(i,N) { ch[i].clear(); unsetXch[i].clear(); } // input Read(N); Fox(i,N) { Read(C[i]),C[i]--; if (C[i]<0) r=i; else { ch[C[i]].pb(i); unsetXch[C[i]].pb(i); } } // perform heavy-light decomposition ind=0; RecCalcSz(r); nxt[r]=r; RecHLD(r); // init curSum=0; Fill(BLT,0); Fill(X,0); Fill(hasSetXUpward,0); // process bribes int ans=1; Fox(i,N) { Bribe(i); ans=ans*(curSum%MOD)%MOD; } // output printf("Case #%d: %d\n",t,ans); } return(0); }