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  • 1401D

    #include <iostream>
    #include <vector>
    #include <algorithm>
    #include <string>
    #include <set>
    #include <queue>
    #include <map>
    #include <sstream>
    #include <cstdio>
    #include <cstring>
    #include <numeric>
    #include <cmath>
    #include <iomanip>
    #include <deque>
    #include <bitset>
    #include <cassert>
    //#include <unordered_set>
    //#include <unordered_map>
    #define ll              long long
    #define pii             pair<int, int>
    #define rep(i,a,b)      for(int  i=a;i<=b;i++)
    #define dec(i,a,b)      for(int  i=a;i>=b;i--)
    #define forn(i, n)      for(int i = 0; i < int(n); i++)
    using namespace std;
    int dir[4][2] = { { 1,0 },{ 0,1 } ,{ 0,-1 },{ -1,0 } };
    const long long INF = 0x7f7f7f7f7f7f7f7f;
    const int inf = 0x3f3f3f3f;
    const double pi = acos(-1.0);
    const double eps = 1e-6;
    const ll mod = 1e9 + 7;
    
    inline ll read()
    {
        ll x = 0; bool f = true; char c = getchar();
        while (c < '0' || c > '9') { if (c == '-') f = false; c = getchar(); }
        while (c >= '0' && c <= '9') x = (x << 1) + (x << 3) + (c ^ 48), c = getchar();
        return f ? x : -x;
    }
    inline ll gcd(ll m, ll n)
    {
        return n == 0 ? m : gcd(n, m % n);
    }
    void exgcd(ll A, ll B, ll& x, ll& y)
    {
        if (B) exgcd(B, A % B, y, x), y -= A / B * x; else x = 1, y = 0;
    }
    inline int qpow(int x, ll n) {
        int r = 1;
        while (n > 0) {
            if (n & 1) r = 1ll * r * x % mod;
            n >>= 1; x = 1ll * x * x % mod;
        }
        return r;
    }
    inline int inv(int x) {
        return qpow(x, mod - 2);
    }
    ll lcm(ll a, ll b)
    {
        return a * b / gcd(a, b);
    }
    /**********************************************************/
    const int N = 1e5 + 5;
    
    int n;
    vector<vector<int>> g;
    ll sz[N];
    ll p[N];
    
    int dfs(int cur, int fa)
    {
        sz[cur] = 1;
        for (auto x : g[cur])
        {
            if (x != fa)
            {
                sz[cur] += dfs(x, cur);
            }
        }
        return sz[cur];
    }
    
    bool cmp(pair<ll,ll> a, pair<ll,ll> b)
    {
        return a.first * a.second < b.first * b.second;
    }
    
    int main()
    {
    #ifdef _DEBUG
        freopen("input.txt", "r", stdin);
        //freopen("output.txt", "w", stdout);
    #endif
        int T;
        cin >> T;
        while (T--)
        {
            int n;
            cin >> n;
            g = vector<vector<int>>(n + 1);
            vector<pair<ll,ll>> v(n);
            rep(i, 1, n - 1)
            {
                int u, v;
                cin >> u >> v;
                g[u].push_back(v);
                g[v].push_back(u);
            }
            int m;
            cin >> m;
            rep(i, 1, m)
                cin >> p[i];
            sort(p + 1, p + m + 1);
            dfs(1, -1);
            int tot = 0;
            rep(i, 2, n)
            {
                v[++tot] = { sz[i],n - sz[i] };
            }
            sort(v.begin() + 1, v.end(), cmp);
            ll ans = 0;
            if (n - 1 >= m)
            {
                int d = n - 1 - m;
                rep(i, 1, d)
                {
                    ans += v[i].first * v[i].second%mod;
                }
                rep(i, 1, m)
                {
                    ans += (v[i + d].first * v[i + d].second % mod) * p[i] % mod;
                }
            }
            else
            {
                ll tmp = 1;
                rep(i, n-1, m)
                    tmp *= p[i], tmp%= mod;
                ans += tmp * (v[n-1].first * v[n-1].second % mod) % mod;
                rep(i, 1, n-2)
                {
                    ans += (v[i].first * v[i].second % mod) * p[i] % mod;
                }
            }
            cout << ans%mod << endl;
        }
        return 0;
    }

    1401D - Maximum Distributed Tree

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  • 原文地址:https://www.cnblogs.com/dealer/p/13650553.html
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