LOJ2359. 「NOIP2016」天天爱跑步【树上差分】

LINK

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思路

首先发现如果对于一个节点，假设一个节点需要统计从字数内来的贡献

需要满足\(dep_u - dep_s = w_u\)
这个条件其实可以转化成\(dep_u - w_u = dep_s\)
然后对于这个东西我们只需要记录下\(dep_s\)的信息就好了
然后考虑差分，把一个询问先分解成\(s->lca\)和\(lca->t\)两部分
接着把连边分别差分处理就可以了

从子树以外的地方的贡献也很好维护

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//Author: dream_maker
#include<bits/stdc++.h>
using namespace std;
//----------------------------------------------
//typename
typedef long long ll;
//convenient for
#define fu(a, b, c) for (int a = b; a <= c; ++a)
#define fd(a, b, c) for (int a = b; a >= c; --a)
#define fv(a, b) for (int a = 0; a < (signed)b.size(); ++a)
//inf of different typename
const int INF_of_int = 1e9;
const ll INF_of_ll = 1e18;
//fast read and write
template <typename T>
void Read(T &x) {
  bool w = 1;x = 0;
  char c = getchar();
  while (!isdigit(c) && c != '-') c = getchar();
  if (c == '-') w = 0, c = getchar();
  while (isdigit(c)) {
    x = (x<<1) + (x<<3) + c -'0';
    c = getchar();
  }
  if (!w) x = -x;
}
template <typename T>
void Write(T x) {
  if (x < 0) {
    putchar('-');
    x = -x; 
  }
  if (x > 9) Write(x / 10);
  putchar(x % 10 + '0');
}
//----------------------------------------------
const int N = 3e5;
struct Node{
  int u, len, typ, dir;
  //typ 1:insert -1:erase
  //dir 1:up 0:down
};
vector<Node> g[N];
struct Edge{
  int v, nxt;
} E[N << 1];
int head[N], tot = 0;
int down[N << 1], up[N << 1];
int Log[N], dep[N], w[N];
int Fa[N][18];
int n, m, ans[N];
void add(int u, int v) {
  E[++tot] = (Edge) {v, head[u]};
  head[u] = tot;
}
void dfs(int u, int fa) {
  dep[u] = dep[fa] + 1;
  Fa[u][0] = fa;
  fu(i, 1, Log[dep[u]]) Fa[u][i] = Fa[Fa[u][i - 1]][i - 1];
  for (int i = head[u]; i; i = E[i].nxt) {
    int v = E[i].v;
    if (v == fa) continue;
    dfs(v, u);
  }
}
int Lca(int u, int v) {
  if (dep[u] < dep[v]) swap(u, v);
  int delta = dep[u] - dep[v];
  fu(i, 0, Log[delta])
    if ((delta >> i) & 1)
     u = Fa[u][i];
  if (u == v) return u;
  int k = Log[dep[u]];
  while (Fa[u][0] != Fa[v][0]) {
    if (Fa[u][k] != Fa[v][k]) {
      u = Fa[u][k];
      v = Fa[v][k];
    }
    k--;
  }
  return Fa[u][0];
}
void solve(int u) {
  ans[u] -= down[w[u] - dep[u] + N] + up[w[u] + dep[u]];
  fv(j, g[u]) {
    Node now = g[u][j];
    if (now.dir) up[now.len] += now.typ;
    else down[now.len] += now.typ;
  }
  for (int i = head[u]; i; i = E[i].nxt) {
    int v = E[i].v;
    if (v == Fa[u][0]) continue;
    solve(v);
  }
  ans[u] += down[w[u] - dep[u] + N] + up[w[u] + dep[u]];
}
int main() {
#ifdef dream_maker 
  freopen("input.txt", "r", stdin);
#endif
  Read(n), Read(m);
  Log[1] = 0; fu(i, 2, n) Log[i] = Log[i >> 1] + 1;
  fu(i, 2, n) {
    int u, v;
    Read(u), Read(v);
    add(u, v);
    add(v, u);
  }
  dfs(1,0);
  fu(i, 1, n) Read(w[i]);
  fu(i, 1, m) {
    int u, v;
    Read(u), Read(v);
    int lca = Lca(u, v);
    g[u].push_back((Node){u, dep[u], 1, 1});
    g[Fa[lca][0]].push_back((Node){Fa[lca][0], dep[u], -1, 1});
    g[v].push_back((Node){v, dep[u] - 2 * dep[lca] + N, 1, 0});
    g[lca].push_back((Node){lca, dep[u] - 2 * dep[lca] + N, -1, 0});
  }
  solve(1);
  fu(i, 1, n) {
    Write(ans[i]);
    putchar(' ');
  }
  return 0;
}