Spoj-qtree 375 query on a tree Chain Division + line segment tree

Operation 1: Modify the K edge weight.

Operation 2: query the maximum edge right between two points.

Tree link segmentation, and the line segment tree maintains the maximum value

# Include <cstdio> # include <cstring> # include <cmath> # include <iostream> # include <algorithm> # include <set> # include <map> # include <queue> # include <vector> # include <string> # define EPS 1e-12 # define INF 0x7fffffff # define maxn 11111 using namespace STD; char STR [maxn]; struct node {int to, next;} e [maxn <1]; int head [maxn], en, N; int Fa [maxn], siz [maxn], top [maxn], son [maxn], W [maxn], DEP [maxn], ID; int Maxs [maxn <2]; int d [maxn] [3]; void Init () {Fa [1] = 0; Dep [1] = 0; id = en = 0; memset (Head,-1, sizeof (head); memset (siz, 0, sizeof (siz); memset (maxs, 0, sizeof (Maxs);} void add (int A, int B) {e [En]. to = B; E [En]. next = head [a]; head [a] = EN ++;} void DFS (INT now) {siz [now] = 1; son [now] = 0; for (INT I = head [now]; ~ I; I = E [I]. Next) {int to = E [I]. To; If (! = Fa [now]) {Fa [to] = now; Dep [to] = Dep [now] + 1; DFS (); if (siz [to]> siz [son [now]) Son [now] = to; siz [now] + = siz [to] ;}} void GETID (INT now, int root) {W [now] = ++ ID; top [now] = root; If (son [now]) GETID (son [now], top [now]); For (INT I = head [now]; ~ I; I = E [I]. Next) {If (E [I].! = Son [now] & E [I].! = Fa [now]) {GETID (E [I]. to, E [I]. to) ;}} void Update (int rt, int L, int R, int K, int add) {If (L = r) {Maxs [RT] = add; return;} int mid = (L + r)/2; int lson = (RT <1); int rson = (RT <1 | 1 ); if (k <= mid) Update (lson, L, mid, K, add); else Update (rson, Mid + 1, R, K, add ); maxs [RT] = max (Maxs [lson], Maxs [rson]);} int query (int rt, int L, int R, int Ql, int QR) {If (QL <= L & R <= QR) return Maxs [RT]; int mid = (L + r)/2; int lson = (RT <1); In T rson = (RT <1 | 1); int TMP = 0; If (QL <= mid) TMP = max (TMP, query (lson, L, mid, Ql, QR); If (QR> mid) TMP = max (TMP, query (rson, Mid + 1, R, Ql, QR); Return TMP ;} int find (int A, int B) {int F1 = top [a]; int F2 = top [B]; int ans = 0; while (F1! = F2) {If (DEP [F1]> Dep [F2]) {ans = max (ANS, query (1, 1, n, W [F1], W [a]); A = Fa [F1]; F1 = top [a];} else {ans = max (ANS, query (1, 1, n, W [F2], W [B]); B = Fa [F2]; F2 = top [B] ;}} if (a = B) Return ans; if (DEP [a]> Dep [B]) ans = max (ANS, query (1, 1, n, W [son [B], W [a]); else ans = max (ANS, query (, N, W [son [a], W [B]); Return ans;} int main () {int cas, a, B, C; scanf ("% d", & CAS); While (CAS --) {Init (); scanf ("% d", & N ); for (INT I = 1; I <n; I ++) {scanf ("% d", & A, & B, & C ); d [I] [0] = A; d [I] [1] = B; d [I] [2] = C; add (A, B ); add (B, A);} DFS (1); GETID (1, 1); For (INT I = 1; I <n; I ++) {If (DEP [d [I] [0]> Dep [d [I] [1]) Swap (d [I] [0], d [I] [1]); // place the edge weight on the son node and change it to vertex weight Update (, N, W [d [I] [1], d [I] [2]);} while (1) {scanf ("% s", STR); If (STR [0] = 'D') break; scanf ("% d", & A, & B); If (STR [0] = 'q') {printf ("% d \ n ", find (A, B);} else {Update (, N, W [d [a] [1], B) ;}} return 0 ;}