HDU 5029 Relief grain --熟练剖分第一题

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <vector>
using namespace std;
#define N 100007

int siz[N];  //子树大小
int son[N];  //重儿子
int dep[N];  //深度
int pos[N];  //在线段树中的位置
int apos[N]; //线段树中位置对应的点
int Top[N];  //所在重链的祖先
int fa[N];   //父节点
int ans[N];  //答案
int head[2*N],tot,POS,n,m;
struct Edge
{
    int v,next;
}G[2*N];

struct Tree
{
    int num,type;
}tree[4*N];

struct node
{
    int u,v,z;
    node(){}
    node(int _u,int _v,int _z):u(_u),v(_v),z(_z){}
};
vector<node> com;
vector<int> Q[N];

void init()
{
    POS = tot = 0;
    memset(head,-1,sizeof(head));
    memset(son,-1,sizeof(son));
    com.clear();
    for(int i=0;i<=n+1;i++)
        Q[i].clear();
}

void addedge(int u,int v)
{
    G[tot].v = v, G[tot].next = head[u], head[u] = tot++;
    G[tot].v = u, G[tot].next = head[v], head[v] = tot++;
}

void pushup(int rt)
{
    if(tree[2*rt].num >= tree[2*rt+1].num)
        tree[rt].type = tree[2*rt].type;
    else
        tree[rt].type = tree[2*rt+1].type;
    tree[rt].num = max(tree[2*rt].num,tree[2*rt+1].num);
}

void build(int l,int r,int rt)
{
    tree[rt].num = 0;
    if(l == r)
    {
        tree[rt].type = l;
        return;
    }
    int mid = (l+r)/2;
    build(l,mid,2*rt);
    build(mid+1,r,2*rt+1);
    pushup(rt);
}

void update(int l,int r,int pos,int val,int rt)
{
    if(l == r)
    {
        tree[rt].num += val;
        return;
    }
    int mid = (l+r)/2;
    if(pos <= mid)
        update(l,mid,pos,val,2*rt);
    else
        update(mid+1,r,pos,val,2*rt+1);
    pushup(rt);
}

void dfs(int u,int f)
{
    dep[u] = dep[f]+1;
    siz[u] = 1;
    for(int i=head[u];i!=-1;i=G[i].next)
    {
        int v = G[i].v;
        if(v == f) continue;
        fa[v] = u;
        dfs(v,u);
        if(son[u] == -1 || siz[v] > siz[son[u]]) son[u] = v;
        siz[u] += siz[v];
    }
}

void dfs2(int u,int father)
{
    pos[u] = ++POS;
    apos[POS] = u;
    Top[u] = father;
    if(son[u] != -1) dfs2(son[u],father);   //有重儿子优先dfs
    for(int i=head[u];i!=-1;i=G[i].next)
    {
        int v = G[i].v;
        if(v != fa[u] && v != son[u])
            dfs2(v,v);
    }
}

void getcom(int u,int v,int z)
{
    int fx = Top[u], fy = Top[v];
    while(fx != fy)
    {
        if(dep[fx] < dep[fy])
        {
            swap(u,v);
            swap(fx,fy);
        }
        com.push_back(node(pos[fx],pos[u],z));
        u = fa[fx];
        fx = Top[u];
    }
    if(dep[u] > dep[v]) swap(u,v);
    com.push_back(node(pos[u],pos[v],z));
}

int main()
{
    int i,j,maxi,u,v,z;
    while(scanf("%d%d",&n,&m)!=EOF && n+m)
    {
        init();
        for(i=1;i<n;i++)
        {
            scanf("%d%d",&u,&v);
            addedge(u,v);
        }
        dep[1] = 0;
        dfs(1,1);
        dfs2(1,1);
        maxi = 1;
        while(m--)
        {
            scanf("%d%d%d",&u,&v,&z);
            getcom(u,v,z);
            maxi = max(maxi,z);
        }
        int SIZE = com.size();
        for(i=0;i<SIZE;i++)
        {
            int u = com[i].u, v = com[i].v, z = com[i].z;
            Q[u].push_back(z);
            Q[v+1].push_back(-z);
        }
        build(1,maxi,1);
        for(i=1;i<=n;i++)
        {
            sort(Q[i].begin(),Q[i].end());
            int sz = Q[i].size();
            for( j=0;j<sz;j++)
            {
                int p = Q[i][j];
                if(p < 0) update(1,maxi,-p,-1,1);
                else      update(1,maxi,p,1,1);
            }
            ans[apos[i]] = tree[1].type;
            if(tree[1].num == 0) ans[apos[i]] = 0;
        }
        for(i=1;i<=n;i++)
            printf("%d\n",ans[i]);
    }
    return 0;
}