Uvalive 7148 LRIP 14 Shanghai Regional Competition K Tree Division

Test instructions n points form a tree with a bit of power. The length of the longest non-descending path, and the difference in the maximum minimum value of the path is not greater than D.

It is clear that the tree is divided, but how to maintain the answer after the partition.

Assuming that the current center of gravity is g, the length of the non-descending path of G is recorded, as well as the maximum value, the length of the non-ascending path and the minimum value respectively.

A map and two points are used here, and the segment tree is also possible, but if you are using a line tree, consider negative values, plus the clear of the line tree and a slightly violent query. The constant size is not good to say.

1#include <bits/stdc++.h>2 using namespacestd;3typedef pair <int,int>PII;4 Const intMAXN = 1e5 +5;5Vector <int>G[MAXN];6 intVAL[MAXN], SIZ[MAXN], N, D;7 BOOLCENTROID[MAXN];8 voidinit () {9      for(inti =0; i < MAXN; i++) {Ten g[i].clear (); One     } Amemset (centroid,false,sizeofcentroid); - } - voidDfsintUintfather) { theSiz[u] =1; -      for(intV:g[u]) { -         if(V! = Father &&!Centroid[v]) { - Dfs (v, u); +Siz[u] + =Siz[v]; -         } +     } A } atPII findcentroid (intUintFatherintt) { -PII res = Make_pair (Int_max,-1); -     ints =1, M =0; -      for(intV:g[u]) { -         if(v = = Father | |Centroid[v]) { -             Continue; in         } -res =min (res, findcentroid (V, U, t)); tom =Max (M, Siz[v]); +s + =Siz[v]; -     } theSiz[u] =s; *m = max (M, ts); $     returnmin (res, Make_pair (M, u));Panax Notoginseng } -Map <int,int>Work ; the voidUpdateintVintLen) { +Auto it =Work.lower_bound (v); A     if(It! = Work.end () && It->second >=Len) { the         return; +     } -WORK[V] =Len; $ } $ voidDFS_UP (intUintFatherintd) { -     if(Val[u] >Val[father]) { -         return; the     } - Update (Val[u], d);Wuyi      for(intV:g[u]) { the         if(V! = Father &&!Centroid[v]) { -Dfs_up (V, u, d+1); Wu         } -     } About } $ intRes; - voidDfs_down (intUintFatherintd) { -     if(Val[u] <Val[father]) { -         return; A     } +Auto it = Work.lower_bound (val[u]-D); the     if(It! =Work.end ()) { -res = max (res, it->second+1+d); $     } the      for(intV:g[u]) { the         if(!centroid[v] && v! =father) { theDfs_down (V, u, d+1); the         } -     } in } the  the voidPresolve (intG, Vector <int> &son) { About work.clear (); theWORK[VAL[G]] =0; the      for(intV:son) { the         if(Val[v] >=Val[g]) { +Dfs_down (V, G,1); -         } the         if(Val[v] <=Val[g]) {BayiDfs_up (V, G,1); the         } the     } - } - voidSolveintu) { theDFS (U,0); the     intg = findcentroid (U,0, Siz[u]). Second; theVector <int>Son; the      for(intV:g[g]) { -         if(!Centroid[v]) { the Son.push_back (v); the         } the     }94 Presolve (g, son); the Reverse (Son.begin (), Son.end ()); the Presolve (g, son); theCENTROID[G] =true;98      for(intV:g[g]) { About         if(!Centroid[v]) { - solve (v);101         }102     }103 }104 intMain () { the    //freopen ("In.txt", "R", stdin);106     intT, CAS =1;107scanf ("%d", &T);108      while(t--) {109 init (); thescanf ("%d%d", &n, &D);111          for(inti =1; I <= N; i++) { thescanf ("%d", val+i);113         } the          for(inti =1; I < n; i++) { the             intu, v; thescanf ("%d%d", &u, &v);117 G[u].push_back (v);118 g[v].push_back (u);119         } -res =1;121Solve1);122printf"Case #%d:%d\n", cas++, res);123     }124     return 0; the}

Uvalive 7148 LRIP 14 Shanghai Regional Competition K Tree Division