标签：Node val int text sum fx gelral CF600E void

两种算法：

• 线段树合并
• \(\text{DSU on tree}\)

#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;

using LL = long long;

namespace SegmentTree_Combination {
    namespace Sg {
    #define mid (l + r >> 1)
        struct Node {
            Node *l, *r;
            LL val, sum;  
        }*nil;
        inline void init(Node *&p) {
            p->l = p->r = nil;
            p->val = p->sum = 0;
        }
        inline void pushup(Node *p) {
            if(p->l->val > p->r->val) p->val = p->l->val, p->sum = p->l->sum;
            else if(p->l->val < p->r->val) p->val = p->r->val, p->sum = p->r->sum;
            else p->val = p->l->val, p->sum = p->l->sum + p->r->sum;
        }
        void update(Node *&p, int l, int r, int x, int v) {
            if(p == nil) init(p = new Node());
            if(l == r) return p->sum = l, p->val += v, void();
            x <= mid ? update(p->l, l, mid, x, v) : update(p->r, mid + 1, r, x, v);
            pushup(p);
        }
        Node *Mg(Node *p, Node *q, int l, int r) {
            if(p == nil) return q; if(q == nil) return p;
            if(l == r) { p->val += q->val, p->sum = l; return p; }
            p->l = Mg(p->l, q->l, l, mid), p->r = Mg(p->r, q->r, mid + 1, r);
            pushup(p); return p;
        }
    }

    int n, col[N];
    LL ret[N];
    vector <int> Link[N];

    struct Sgtree {
        Sg::Node *rt;
        inline void update(int x, int v) { Sg::update(rt, 1, n, x, v); }
        inline void Merge(Sgtree *that) { rt = Sg::Mg(this->rt, that->rt, 1, n); }
        inline LL query() { return rt->sum; }
    }s[N];

    void dfs(int u, int F) {
        s[u].update(col[u], 1);
        for(auto v : Link[u]) {
            if(v == F) continue;
            dfs(v, u);
            s[u].Merge(&s[v]);
        }
        ret[u] = s[u].query();
    }

    signed main() {
    #ifndef ONLINE_JUDGE
        freopen("in.txt", "r", stdin);
        freopen("Ans.txt", "w", stdout);
    #endif
        Sg::init(Sg::nil = new Sg::Node());
        scanf("%d", &n);
        for(int i = 1; i <= n; ++i) scanf("%d", col + i);
        for(int i = 1; i < n; ++i) {
            register int x, y;
            scanf("%d %d", &x, &y);
            Link[x].push_back(y);
            Link[y].push_back(x);
        }
        for(int i = 1; i <= n; ++i) s[i].rt = Sg::nil;
        dfs(1, 0);
        for(int i = 1; i <= n; ++i) printf("%lld ", ret[i]);
        return 0;
    }
}

namespace DSU_on_tree {
    LL ans[N], bucket[N], mx, sum;
    int sz[N], gx[N], col[N];
    vector <int> Link[N];

    int n;

    void getson(int u, int fx) {
        sz[u] = 1;
        int mx = 0, p = 0;
        for(auto v : Link[u]) {
            if(v == fx) continue;
            getson(v, u);
            sz[u] += sz[v];
            if(sz[v] > mx) mx = sz[v], p = v;
        }
        if(p) gx[p] = 1;
    }

    void dfs(int u, int fx, int p) {
        if(++bucket[col[u]] > mx) mx = bucket[col[u]], sum = col[u];
        else if(bucket[col[u]] == mx) sum += col[u];
        for(auto v : Link[u]) if(v != fx && v != p) dfs(v, u, p);
    }

    void init(int u, int fx) {
        --bucket[col[u]];
        for(auto v : Link[u]) if(v != fx) init(v, u);
    }

    void dsu(int u, int fx) {
        int p = 0;
        for(auto v : Link[u]) {
            if(v == fx) continue;
            if(!gx[v]) dsu(v, u), init(v, u), sum = mx = 0;
            else p = v;
        }
        if(p) dsu(p, u);
        dfs(u, fx, p);
        ans[u] = sum;
    }

    signed main() {
    #ifndef ONLINE_JUDGE
        freopen("in.txt", "r", stdin);
        freopen("Ans.txt", "w", stdout);
    #endif
        scanf("%d", &n);
        for(int i = 1; i <= n; ++i) scanf("%d", col + i);
        for(int i = 1, x, y; i < n; ++i) {
            scanf("%d %d", &x, &y);
            Link[x].push_back(y), Link[y].push_back(x);
        }
        getson(1, 0);
        dsu(1, 0);
        for(int i = 1; i <= n; ++i) printf("%lld ", ans[i]);
        return 0;
    }
}

//signed main() { return SegmentTree_Combination::main(); }
signed main() { return DSU_on_tree::main(); }

标签：Node,val,int,text,sum,fx,gelral,CF600E,void
来源： https://www.cnblogs.com/Doge297778/p/16611139.html

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