"Spoj qtree" tree chain split template

Use the line tree to solve, note that because the path is the maximum value, pay attention to the details.

#include <cstdio> #include <cstring> #include <algorithm>using namespace std;const int maxn = 10010;# Define Lson (pos<<1) #define RSON (pos<<1|1) const int INF = (1 <<); int n;//-------------------------- ------------------------struct edge{int to,next;} EDGE[MAXN * 2];int head[maxn],tot;int top[maxn];int fa[maxn];int deep[maxn];int num[maxn];int p[MAXN];int fp[MAXN];int    Son[maxn];int pos;void init () {tot = 0;    memset (head,-1,sizeof (head));    pos = 1; memset (son,-1,sizeof (son));    void Addedge (int u,int v) {edge[tot].to = v;    Edge[tot].next = Head[u]; Head[u] = tot + +;}    void dfs1 (int u,int pre,int d) {deep[u] = D;    Fa[u] = pre;    Num[u] = 1;        for (int i = head[u]; i =-1; i = edge[i].next) {int v = edge[i].to;            if (v! = Pre) {DFS1 (v,u,d + 1);            Num[u] + = Num[v]; if (son[u] = = 1 | | num[v] > NUM[SON[U]]) son[u] = v; Looking for a heavy son}}}void getpos (int u,int sp) {Top[u]= SP;    P[u] = pos++;    printf ("%d%d\n", U,p[u]);    Fp[p[u]] = u;    if (son[u] = =-1) return;    GetPos (SON[U],SP);        for (int i = head[u]; i =-1; i = edge[i].next) {int v = edge[i].to;    if (v! = son[u] && v!= fa[u]) GetPos (V,V);            }}//----------------------------------------------int MAXV[MAXN << 2]; The one side void build () {memset (maxv,0,sizeof (MAXV));} void pushup (int pos) {Maxv[pos] = max (Maxv[lson],maxv[rson]);}        void update (int l,int r,int to,int value,int pos) {if (L = = r) {Maxv[pos] = value;    Return    } int mid = (L + r) >> 1;    if (to <= mid) update (L,mid,to,value,lson);    else Update (mid + 1,r,to,value,rson); Pushup (POS);}    int query (int l,int r,int l,int r,int pos) {if (L <= l && R <= R) return Maxv[pos];    int mid = (L + r) >> 1;    int ret =-INF;    if (L <= mid) ret = max (Ret,query (L,mid,l,r,lson)); if (R > mid) ret = max(Ret,query (mid + 1,r,l,r,rson)); return ret;}    -------------------------------------------------------int find (int u,int v) {int f1 = TOP[U],F2 = Top[v];    int tmp = 0;            while (f1! = F2) {if (Deep[f1] < DEEP[F2]) {swap (F1,F2);        Swap (U,V);        } TMP = max (Tmp,query (1,pos,p[f1],p[u],1));        U = fa[f1];    F1 = Top[u];    } if (U = = v) return tmp;    if (Deep[u] > Deep[v]) swap (U,V); Return Max (Tmp,query (1,pos,p[son[u]],p[v],1));} ----------------------------------------------------------struct e{int from,to,value;}    E[maxn];int Main () {int T;    int u,v;    scanf ("%d", &t);        while (t--) {scanf ("%d", &n);        Init ();            for (int i = 0; i < n-1; i++) {scanf ("%d%d%d", &e[i].from,&e[i].to,&e[i].value);            Addedge (e[i].from,e[i].to);        Addedge (E[i].to,e[i].from);        } DFS1 (1,0,0);        GetPos (a);        Build (); for (int i = 0; i < n-1; i++) {if (Deep[e[i].from] > Deep[e[i].to]) swap (e[i].from,e[i].to);        Here is updating a line segment, not a dot update (1,pos,p[e[i].to],e[i].value,1);        } Char op[10];            while (scanf ("%s", op)! = EOF) {if (op[0] = = ' D ') break;            scanf ("%d%d", &u,&v);            if (op[0] = = ' Q ') {printf ("%d\n", Find (u,v));            } else{Update (1,pos,p[e[u-1].to],v,1);    }} if (T) puts (""); } return 0;}

Copyright NOTICE: This article for Bo Master original article, without Bo Master permission not reproduced.

"Spoj qtree" tree chain split template