【比较函数坑点】D. Li Hua and Tree

题目

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pb push_back
#define fi first
#define se second
#define lson p << 1
#define rson p << 1 | 1
const int maxn = 1e5 + 5, inf = 1e18, maxm = 4e4 + 5;
const int mod = 1e9 + 7;
// const int mod = 998244353;
const int N = 1e6;
// int a[505][5005];
// bool vis[505][505];
// char s[505][505];
int a[maxn], b[maxn];
bool vis[maxn];
string s;
int n, m;

int siz[maxn];
struct Node{
    // int val, id;
    // bool operator<(const Node &u)const{
    //     return val < u.val;
    // }
    int siz, id;
    bool operator<(const Node &u)const{
        // if(siz[id] != siz[u.id])
        //     return siz[id] > siz[u.id];
        // return id < u.id;不能用利用全局数组比较，因为siz数组也在更新，可能出现set排序不及时的情况
        if(siz != u.siz){
            return siz > u.siz;
        }
        return id < u.id;
    }
}c[maxn];

int ans[maxn];
// priority_queue<Node> G[maxn];
set<Node> G[maxn];
int f[maxn], fa[maxn];
vector<int> g[maxn];

void dfs(int u, int p){
    fa[u] = p;
    f[u] = a[u];
    siz[u] = 1;
    for(auto v : g[u]){
        // int v = z.id;
        if(v == p) continue;
        dfs(v, u);
        G[u].insert({siz[v], v});
        // G[u].insert({v});
        siz[u] += siz[v];
        f[u] += f[v];
    }
}

void solve(){
    int res = 0;
    int q, k;
    cin >> n >> m;
    for(int i = 1; i <= n; i++){
        cin >> a[i];
    }
    for(int i = 1; i < n; i++){
        int u, v;
        cin >> u >> v;
        g[u].pb(v);
        g[v].pb(u);
    }
    dfs(1, 1);
    for(int tt = 1; tt <= m; tt++){
        int op, x;
        cin >> op >> x;
        if(op == 1){
            cout << f[x] << '\n';
        }
        else{
            if(G[x].size() == 0) continue;
            int par = fa[x];
            int son = G[x].begin() -> id;
            int tmp;
            G[x].erase(Node{siz[son], son});
            G[par].erase(Node{siz[x], x});
            tmp = siz[x];
            siz[x] -= siz[son];
            siz[son] += tmp - siz[son];
            G[son].insert(Node{siz[x], x});
            G[par].insert(Node{siz[son], son});
            tmp = f[x];
            f[x] -= f[son];
            f[son] += tmp - f[son];
            fa[son] = par;
            fa[x] = son;
        }  
    }
}
    
signed main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    int T = 1;
    // cin >> T;
    while (T--)
    {
        solve();
    }
    
    return 0;
}