Luogu P3313 [SDOI2014]旅行

题目链接：​​传送门​​

动态开点+树剖的
模板吧。
都很熟的话
就挺好写的
特别注意在dfs序上修改

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <complex>
#include <algorithm>
#include <climits>
#include <queue>
#include <map>
#include <set>
#include <random>
#include <vector>
#include <iomanip>
#define
#define

using namespace std;
typedef long long ll;
int cnt, n, m, rt[B], a[B], b[B];
namespace Seg {
  struct node {
    int l, r, w, mx;
  }tree[A << 1];
  void up(int k) {
    tree[k].w = tree[tree[k].l].w + tree[tree[k].r].w;
    tree[k].mx = max(tree[tree[k].l].mx, tree[tree[k].r].mx);
  }
  void change(int &k, int l, int r, int pos, int val) {
    if (!k) k = ++cnt;
    if (l == r) {
      tree[k].w = tree[k].mx = val;
      return;
    }
    int m = (l + r) >> 1;
    if (pos <= m) change(tree[k].l, l, m, pos, val);
    else change(tree[k].r, m + 1, r, pos, val);
    up(k);
  }
  void dele(int &k, int l, int r, int pos) {
    if (!k) return;
    if (l == r) {
      tree[k].w = tree[k].mx = 0;
      return;
    }
    int m = (l + r) >> 1;
    if (pos <= m) dele(tree[k].l, l, m, pos);
    else dele(tree[k].r, m + 1, r, pos);
    up(k);
  }
  int asksum(int &k, int l, int r, int nowl, int nowr) {
    if (!k) return 0;
    if (nowl >= l and nowr <= r) return tree[k].w;
    int ans = 0, m = (nowl + nowr) >> 1;
    if (l <= m) ans += asksum(tree[k].l, l, r, nowl, m);
    if (r > m) ans += asksum(tree[k].r, l, r, m + 1, nowr);
    return ans;
  }
  int askmax(int &k, int l, int r, int nowl, int nowr) {
    if (!k) return 0;
    if (nowl >= l and nowr <= r) return tree[k].mx;
    int ans = 0, m = (nowl + nowr) >> 1;
    if (l <= m) ans = max(ans, askmax(tree[k].l, l, r, nowl, m));
    if (r > m) ans = max(ans, askmax(tree[k].r, l, r, m + 1, nowr));
    return ans;
  }
}
int dfn[B], pre[B], top[B], siz[B], son[B], dep[B], cntt, fa[B];
namespace Cut {
  struct node {
    int next, to;
  }e[B << 1];
  int head[B << 1], num;
  void add(int fr, int to) {
    e[++num].next = head[fr];
    e[num].to = to;
    head[fr] = num;
  }
  void prepare(int fr) {
    siz[fr] = 1;
    for (int i = head[fr]; i; i = e[i].next) {
      int ca = e[i].to;
      if (ca == fa[fr]) continue;
      fa[ca] = fr;
      dep[ca] = dep[fr] + 1;
      prepare(ca);
      siz[fr] += siz[ca];
      if (siz[ca] > siz[son[fr]]) son[fr] = ca;
    }
  }
  void dfs(int fr, int tp) {
    dfn[fr] = ++cntt, pre[cntt] = fr, top[fr] = tp;
    if (!son[fr]) return;
    dfs(son[fr], tp);
    for (int i = head[fr]; i; i = e[i].next) {
      int ca = e[i].to;
      if (ca == son[fr] or ca == fa[fr]) continue;
      dfs(ca, ca);
    }
  }
  int asksum(int x, int y, int ans = 0) {
    int pos = b[x];
    while (top[x] != top[y]) {
      if (dep[top[x]] < dep[top[y]]) swap(x, y);
      ans += Seg::asksum(rt[pos], dfn[top[x]], dfn[x], 1, n);
      x = fa[top[x]];
    }
    if (dep[x] > dep[y]) swap(x, y);
    ans += Seg::asksum(rt[pos], dfn[x], dfn[y], 1, n);
    return ans;
  }
  int askmax(int x, int y, int ans = 0) {
    int pos = b[x];
    while (top[x] != top[y]) {
      if (dep[top[x]] < dep[top[y]]) swap(x, y);
      ans = max(ans, Seg::askmax(rt[pos], dfn[top[x]], dfn[x], 1, n));
      x = fa[top[x]];
    }
    if (dep[x] > dep[y]) swap(x, y);
    ans = max(ans, Seg::askmax(rt[pos], dfn[x], dfn[y], 1, n));
    return ans;
  }
}

int main(int argc, char const *argv[]) {
  scanf("%d%d", &n, &m); int x, y, c, w;
  for (int i = 1; i <= n; i++) scanf("%d%d", &a[i], &b[i]);
  for (int i = 2; i <= n; i++) {
    scanf("%d%d", &x, &y);
    Cut::add(x, y); Cut::add(y, x);
  }
  Cut::prepare(1); Cut::dfs(1, 1);
  for (int i = 1; i <= n; i++) Seg::change(rt[b[pre[i]]], 1, n, i, a[pre[i]]);
  while (m--) {
    char opt[2]; scanf("%s", opt);
    if (opt[1] == 'C') {
      scanf("%d%d", &x, &c);
      Seg::dele(rt[b[x]], 1, n, dfn[x]);
      b[x] = c;
      Seg::change(rt[b[x]], 1, n, dfn[x], a[x]);
    }
    if (opt[1] == 'W') {
      scanf("%d%d", &x, &w);
      Seg::dele(rt[b[x]], 1, n, dfn[x]);
      a[x] = w;
      Seg::change(rt[b[x]], 1, n, dfn[x], a[x]);
    }
    if (opt[1] == 'S') {
      scanf("%d%d", &x, &y);
      printf("%d\n", Cut::asksum(x, y));
    }
    if (opt[1] == 'M') {
      scanf("%d%d", &x, &y);
      printf("%d\n", Cut::askmax(x, y));
    }
  }
}