LuoguP3806 模板点分治1 (点分治)

Posted 2022-04-18 bingoyes

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#define R(a,b,c) for(register int  a = (b); a <= (c); ++ a)
#define nR(a,b,c) for(register int  a = (b); a >= (c); -- a)
#define Max(a,b) ((a) > (b) ? (a) : (b))
#define Min(a,b) ((a) < (b) ? (a) : (b))
#define Fill(a,b) memset(a, b, sizeof(a))
#define Swap(a,b) a^=b^=a^=b
#define ll long long
#define ON_DEBUG

#ifdef ON_DEBUG

#define D_e_Line printf("\n\n----------\n\n")

#else

#define D_e_Line ;

#endif

struct ios
    template<typename ATP>ios& operator >> (ATP &x)
        x = 0; int f = 1; char c;
        for(c = getchar(); c < '0' || c > '9'; c = getchar()) if(c == '-')  f = -1;
        while(c >= '0' && c <= '9') x = x * 10 + (c ^ '0'), c = getchar();
        x*= f;
        return *this;
    
io;
using namespace std; 
const int N = 10007;
const int MAXX = 10000000;

struct Edge
    int nxt,pre,w;
e[N<<1];
int cntEdge,head[N];
inline void add(int u,int v,int w)
    e[++cntEdge] = (Edge)head[u], v, w, head[u] = cntEdge;


int minn, root, treeSize;

int vis[N],siz[N];
inline void GetRoot(int u,int fa)
    siz[u] = 1;
    int sum = 0;
    for(register int i = head[u]; i; i = e[i].nxt)
        int v = e[i].pre;
        if(vis[v] || v == fa) continue;
        GetRoot(v, u);
        sum = Max(sum, siz[v]);
        siz[u] += siz[v];
    
    sum = Max(sum, treeSize - siz[u]);
    if(sum < minn)
        minn = sum;
        root = u;
    


int dis[N];

int tot;
inline void GetDistance(int u,int fa,int w)
    dis[++tot] = w;
    for(register int i = head[u]; i; i = e[i].nxt)
        int v = e[i].pre;
        if(vis[v] || v == fa) continue;
        GetDistance(v, u, w + e[i].w);
    


int num[MAXX];
inline void Solve(int u,int w,int flag) // w is the influence of the beginning node
    tot = 0;
    GetDistance(u, u, 0);
    R(i,1,tot)
        R(j,1,tot)
            if(flag && dis[i] + dis[j] <= MAXX)
                ++ num[dis[i] + dis[j]];
            else
                if(dis[i] + dis[j] +w <= MAXX)
                    -- num[dis[i] + dis[j] + w];
        
    


inline void DFS(int u)
    Solve(u, 0, 1);
    vis[u] = true;
    for(register int i = head[u]; i; i = e[i].nxt)
        int v = e[i].pre;
        if(vis[v]) continue;
        Solve(v, (e[i].w << 1), 0); // QAQ // \ T^T /
        treeSize = siz[v];
        minn = 0x7fffffff;
        GetRoot(v, u);
        DFS(root);
    


int main()
    int n,m;
    io >> n >> m;
    R(i,2,n)
        int u,v,w;
        io >> u >> v >> w;
        add(u, v, w);
        add(v, u, w);
    
    
    treeSize = n; // because I forgot this sentence, the whole morning...
    minn = 0x7fffffff;
    GetRoot(1, 1);
    DFS(root);
    
    while(m--)
        int x;
        io >> x;
        if(num[x])
            printf("AYE\n");
        else
            printf("NAY\n");
    
    
    return 0;