Codeforces375D Tree and Queries

dsu on tree

题目链接

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题目大意

解题思路

AC_Code

#include<bits/stdc++.h>
#define rep(i,a,n) for (int i=a;i<=n;i++)
#define per(i,n,a) for (int i=n;i>=a;i--)
#define int long long
#define pb push_back
#define fi first
#define se second
using namespace std;
const int N = 3e5 + 10;
struct Tree{
int l , r , lazy , sum;
}tree[N << 2];
void push_up(int rt)
{
tree[rt].sum = tree[rt << 1].sum + tree[rt << 1 | 1].sum;
}
void push_down(int rt)
{
int x = tree[rt].lazy;
tree[rt].lazy = 0;
tree[rt << 1].lazy = tree[rt << 1 | 1].lazy = x;
tree[rt << 1].sum += (tree[rt << 1].r - tree[rt << 1].l + 1) * x;
tree[rt << 1 | 1].sum += (tree[rt << 1 | 1].r - tree[rt << 1 | 1].l + 1) * x;
}
void build(int l , int r , int rt)
{
tree[rt].l = l , tree[rt].r = r , tree[rt].lazy = 0;
if(l == r)
{
tree[rt].sum = 0;
return ;
}
int mid = l + r >> 1;
build(l , mid , rt << 1);
build(mid + 1 , r , rt << 1 | 1);
push_up(rt);
}
void update_range(int L , int R , int rt , int val)
{
int l = tree[rt].l , r = tree[rt].r;
if(L <= l && r <= R)
{
tree[rt].lazy += val;
tree[rt].sum += (r - l + 1) * val;
return ;
}
push_down(rt);
int mid = l + r >> 1;
if(L <= mid) update_range(L , R , rt << 1 , val);
if(R > mid)  update_range(L , R , rt << 1 | 1 , val);
push_up(rt);
}
int query_range(int L , int R , int rt)
{
int l = tree[rt].l , r = tree[rt].r;
if(L <= l && r <= R) return tree[rt].sum;
push_down(rt);
int mid = l + r >> 1 , ans = 0;
if(L <= mid) ans += query_range(L , R , rt << 1);
if(R > mid)  ans += query_range(L , R , rt << 1 | 1);
return ans;
}
struct Edge{
int nex , to;
}edge[N << 1];
int head
 , TOT;
void add_edge(int u , int v)
{
edge[++ TOT].nex = head[u] ;
edge[TOT].to = v;
head[u] = TOT;
}
int dep
 , sz
 , hson
 , HH;
int col
 , n , m , up;
int cnt
 , sum
;
vector<pair<int , int>>Q
 , ans;
void dfs(int u , int far)
{
dep[u] = dep[far] + 1;
sz[u] = 1;
for(int i = head[u] ; i ; i = edge[i].nex)
{
int v = edge[i].to;
if(v == far) continue ;
dfs(v , u);
sz[u] += sz[v];
if(sz[v] > sz[hson[u]]) hson[u] = v;
}
}
void calc(int u , int far,  int val)
{
cnt[col[u]] += val;
if(val == 1)
{
int k = cnt[col[u]];
update_range(k , k , 1 , 1);
}
if(val == -1)
{
int k = cnt[col[u]] + 1;
update_range(k , k , 1 , -1);
}
for(int i = head[u] ; i ; i = edge[i].nex)
{
int v = edge[i].to;
if(v == far || v == HH) continue ;
calc(v , u , val);
}
}
void dsu(int u , int far , int op)
{
for
ad8
(int i = head[u] ; i ; i = edge[i].nex)
{
int v = edge[i].to;
if(v == far || v == hson[u]) continue ;
dsu(v , u , 0);
}
if(hson[u]) dsu(hson[u] , u , 1) , HH = hson[u];
calc(u , far , 1);
for(auto i : Q[u])
{
int id = i.fi , k = i.se;
int res = query_range(k , k , 1);
ans.pb(make_pair(id , res));
}
HH = 0;
if(!op) calc(u , far , -1);
}
signed main()
{
ios::sync_with_stdio(false);
cin.tie(0) , cout.tie(0);
cin >> n >> m;
rep(i , 1 , n) cin >> col[i];
rep(i , 1 , n - 1)
{
int u , v;
cin >> u >> v;
add_edge(u , v) , add_edge(v , u);
}
rep(i , 1 , m)
{
int u , k;
cin >> u >> k;
Q[u].pb(make_pair(i , k));
}
build(1 , 100000 , 1);
dfs(1 , 0);
dsu(1 , 0 , 0);
sort(ans.begin() , ans.end());
for(auto i : ans) cout << i.se << '\n';
return 0;
}