CF EDU - E. Lomsat gelral 树上启发式合并

学习：http://codeforces.com/blog/entry/44351

E. Lomsat gelral

题意：

给定一个以1为根节点的树，每个节点都有一个颜色，问每个节点的子树中，颜色最多的是哪几种颜色，输出这些颜色的值得和。

思路：

树上启发式合并的模板题，具体来说，先对树进行树链剖分，分出一个重链和轻边，dfs时，把每条轻儿子暴力加到根节点中，每次加的时候，用这样的技巧

if(csz < cnt[col[v]]) sum = col[v] , csz = cnt[col[v]];

else if(csz==cnt[col[v]]) sum += col[v];

就可以使得sum中保存的是这个节点的子树中数量相同且最多的颜色和。

#include <iostream>

#include <cstdio>

#include <algorithm>

#include <cstring>

#include <string>

#include <vector>

#include <map>

#include <set>

#include <queue>

#include <list>

#include <cstdlib>

#include <iterator>

#include <cmath>

#include <iomanip>

#include <bitset>

#include <cctype>

using namespace std;

//#pragma comment(linker, "/STACK:102400000,102400000")  //c++

#define lson (l , mid , rt << 1)

#define rson (mid + 1 , r , rt << 1 | 1)

#define debug(x) cerr << #x << " = " << x << "\n";

#define pb push_back

#define pq priority_queue

typedef long long ll;

typedef unsigned long long ull;

typedef pair<ll ,ll > pll;

typedef pair<int ,int > pii;

//priority_queue<int> q;//这是一个大根堆q

//priority_queue<int,vector<int>,greater<int> >q;//这是一个小根堆q

#define fi first

#define se second

#define endl '\n'

#define OKC ios::sync_with_stdio(false);cin.tie(0)

#define FT(A,B,C) for(int A=B;A <= C;++A)  //用来压行

#define REP(i , j , k)  for(int i = j ; i <  k ; ++i)

//priority_queue<int ,vector<int>, greater<int> >que;

const ll mos = 0x7FFFFFFF;  //

const ll nmos = 0x80000000;  //-2147483648

const int inf = 0x3f3f3f3f;

const ll inff = 0x3f3f3f3f3f3f3f3f; //

template<typename T>

inline T read(T&x){

    x=;int f=;char ch=getchar();

    while (ch<''||ch>'') f|=(ch=='-'),ch=getchar();

    while (ch>=''&&ch<='') x=x*+ch-'',ch=getchar();

    return x=f?-x:x;

}

// #define _DEBUG;         //*//

#ifdef _DEBUG

freopen("input", "r", stdin);

// freopen("output.txt", "w", stdout);

#endif

/*-----------------show time----------------*/

                const int maxn = 1e5+;

                vector<int>g[maxn];

                vector<int>v[maxn];

                int cnt[maxn],col[maxn];

                ll ans[maxn];

                bool big[maxn];

                int n;

                int sz[maxn];

                void dfs1(int v,int fa){

                    sz[v] = ;

                    for(int i=; i<g[v].size(); i++){

                        int u = g[v][i];

                        if(u!=fa){

                            dfs1(u,v);

                            sz[v]+=sz[u];

                        }

                    }

                }

                ll sum = ,csz = ;

                // priority_queue<int>que;

                void add(int v, int fa,int x){

                    cnt[col[v]] += x;

                    // if(v==1)cout<<"$$"<<cnt[col[v]]<<endl;

                    if(csz < cnt[col[v]]) sum = col[v] , csz = cnt[col[v]];

                    else if(csz==cnt[col[v]]) sum += col[v];

                    for(int i=;i<g[v].size(); i++){

                        int u = g[v][i];

                        if(u!=fa && big[u]==){

                            add(u,v,x);

                        }

                    }

                }

                void dfs(int v,int fa,int keep){

                    int mx = -,bigChild = -;

                    for(int i=; i<g[v].size(); i++){

                        int u = g[v][i];

                        if(u!=fa && sz[u] > mx)

                            mx = sz[u], bigChild = u;

                    }

                    for(int i=; i<g[v].size(); i++){

                        int u = g[v][i];

                        if(u!=fa && u!=bigChild){

                            dfs(u,v,);////////////

                        }

                    }

                    if(bigChild!=-){

                        dfs(bigChild,v,),big[bigChild] = ;/////////

                    }

                    add(v,fa,);            ////////

                    ans[v] = sum;

                    /*

                    debug(v);

                    for(int i=1; i<=n; i++){

                        cout<<cnt[i]<<" ";

                    }

                    cout<<endl;

                    */

                    if(bigChild!=-) big[bigChild] = ;

                    if(keep==){

                        add(v,fa,-);

                        sum = ;csz = ;

                    }

                    /*

                    debug(v);

                    for(int i=1; i<=n; i++){

                        cout<<cnt[i]<<" ";

                    }

                    cout<<endl;

                    */

                }

int main(){

                scanf("%d", &n);

                for(int i=; i<=n; i++)scanf("%d", &col[i]);

                for(int i=; i<n; i++){

                    int u,v;

                    scanf("%d%d", &u, &v);

                    g[u].pb(v);

                    g[v].pb(u);

                }

                dfs1(,);

                dfs(,,);

                for(int i=; i<=n; i++)printf("%lld " , ans[i]);

                printf("\n");

                return ;

}

EDU#2E