CODEVS1380 Prom with no boss (tree DP)

F[I,0] indicates that the first person does not attend the dance

f[i,1] indicates that the first person attends the dance

F[i,1]=sigma (f[j,0]) +v[i] J for Children of I

F[i,1]=sigma (Max (f[j,0],f[j,1)) J for Children of I

Ans=max (f[root,0],f[root,1])

Program CODEVS1380;typeArr=RecordU,v,next:longint; End;Constmaxn=10000;varegArray[0.. MAXN] ofarr; Last:Array[0.. MAXN] ofLongint; A:Array[0.. MAXN] ofLongint; F:Array[0.. MAXN,0..1] ofLongint; FA:Array[0.. MAXN] ofLongint; I,n,u,v,j,root:longint;procedureAdd (u,v:longint);beginInc (J); EG[J].U:=u; EG[J].V:=v; Eg[j].next:=Last[u]; Last[u]:=J;End;functionMax (a,b:longint): Longint;begin  ifA>b ThenExit (a)Elseexit (b);End;procedureDFS (u:longint);varI,v,sum1,sum2:longint;begin  iflast[u]=-1  Then    beginF[u,0]:=0; F[u,1]:=A[u];    Exit End; I:=last[u]; sum1:=0; sum2:=0;  whilei<>-1  Do    beginV:=eg[i].v;      DFS (v); SUM1:=sum1+f[v,0]; SUM2:=sum2+max (F[v,0],f[v,1]); I:=Eg[i].next; End; F[u,0]:=sum2; F[u,1]:=sum1+A[u];End;beginREADLN (n); J:=-1;  fori:=1  toMaxn Dolast[i]:=-1;  fori:=1  toN Doreadln (A[i]);  READLN (V,u);  while(v<>0) and(u<>0) Do    beginFa[v]:=u;      Add (U,V);    READLN (V,u); End;  fori:=1  toN Do iffa[i]=0  Thenroot:=i;    DFS (root); Writeln (Max (F[root,0],f[root,1]));End.

CODEVS1380 prom with no boss (tree DP)