CodeForces-1009F Dominant Indeces

传送门：CodeForces-1009F

思路分析

线段树合并的话要注意空间，开一个栈存没用的点，然后搞搞就行了

树上启发式合并代码

#include <bits/stdc++.h>
#define ls x<<1
#define rs x<<1|1
#define fi first
#define se second
#define ll long long
#define pb push_back
#define mp make_pair
#define fun function
#define sz(x) (x).size()
#define lowbit(x) (x)&(-x)
#define all(x) (x).begin(),(x).end()
#define mem(a,b) memset(a,b,sizeof(a))

namespace FastIO {
#define BUF_SIZE 100000
#define OUT_SIZE 100000
    bool IOerror=0;
    inline char nc() {
        static char buf[BUF_SIZE],*p1=buf+BUF_SIZE,*pend=buf+BUF_SIZE;
        if(p1==pend) {
            p1=buf;
            pend=buf+fread(buf,1,BUF_SIZE,stdin);
            if(pend==p1) {
                IOerror=1;
                return -1;
            }
        }
        return *p1++;
    }
    inline bool blank(char ch) {
        return ch==' '||ch=='\n'||ch=='\r'||ch=='\t';
    }
    template<class T> inline bool read(T &x) {
        bool sign=0;
        char ch=nc();
        x=0;
        for(; blank(ch); ch=nc());
        if(IOerror)return false;
        if(ch=='-')sign=1,ch=nc();
        for(; ch>='0'&&ch<='9'; ch=nc())x=x*10+ch-'0';
        if(sign)x=-x;
        return true;
    }
    template<class T,class... U>bool read(T& h,U&... t) {
        return read(h)&&read(t...);
    }
#undef OUT_SIZE
#undef BUF_SIZE
};
using namespace std;
using namespace FastIO;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int INF = 0x3f3f3f3f;
const int N = 1e6+10;

vector<int>e[N];
int siz[N],dep[N],son[N],ans[N],sum[N];

void dfs1(int u,int fa) {
    dep[u]=dep[fa]+1;
    siz[u]=1;
    int maxlen=0;
    for(auto v:e[u]) {
        if(v==fa) continue;
        dfs1(v,u);
        siz[u]+=siz[v];
        if(siz[v]>siz[son[u]]) son[u]=v;
    }
}

int ma,res;

void add(int u,int fa) {
    sum[dep[u]]++;
    if(sum[dep[u]]==ma) res=min(res,dep[u]);
    if(sum[dep[u]]>ma){
        ma=sum[dep[u]];
        res=dep[u];
    }
    for(auto v:e[u]) if(v!=fa) add(v,u);
}

void del(int u,int fa) {
    sum[dep[u]]--;
    for(auto v:e[u]) if(v!=fa) del(v,u);
}

void dfs2(int u,int fa) {
    for(auto v:e[u]) {
        if(v==fa || v==son[u]) continue;
        dfs2(v,u);
        del(v,u);
        ma=-1;
    }
    if(son[u]) dfs2(son[u],u);
    for(auto v:e[u]) {
        if(v==son[u] || v==fa) continue;
        add(v,u);
    }
    sum[dep[u]]++;
    if(sum[dep[u]]==ma) res=min(res,dep[u]);
    if(sum[dep[u]]>ma){
        ma=sum[dep[u]];
        res=dep[u];
    }
    ans[u]=res-dep[u];
}

int main() {

#ifdef xiaofan
    freopen("1.in","r",stdin);
    freopen("1.out","w",stdout);
#endif

    int n;
    read(n);
    for(int i=1; i<n; i++) {
        int u,v;
        read(u,v);
        e[u].pb(v);
        e[v].pb(u);
    }
    dfs1(1,0);
    dfs2(1,0);
    for(int i=1; i<=n; i++) printf("%d\n",ans[i]);




    return 0;
}

线段树合并代码

#include <bits/stdc++.h>
#define fi first
#define se second
#define ll long long
#define pb push_back
#define mp make_pair
#define fun function
#define sz(x) (x).size()
#define lowbit(x) (x)&(-x)
#define all(x) (x).begin(),(x).end()
#define mem(a,b) memset(a,b,sizeof(a))

namespace FastIO {
#define BUF_SIZE 100000
#define OUT_SIZE 100000
    bool IOerror=0;
    inline char nc() {
        static char buf[BUF_SIZE],*p1=buf+BUF_SIZE,*pend=buf+BUF_SIZE;
        if(p1==pend) {
            p1=buf;
            pend=buf+fread(buf,1,BUF_SIZE,stdin);
            if(pend==p1) {
                IOerror=1;
                return -1;
            }
        }
        return *p1++;
    }
    inline bool blank(char ch) {
        return ch==' '||ch=='\n'||ch=='\r'||ch=='\t';
    }
    template<class T> inline bool read(T &x) {
        bool sign=0;
        char ch=nc();
        x=0;
        for(; blank(ch); ch=nc());
        if(IOerror)return false;
        if(ch=='-')sign=1,ch=nc();
        for(; ch>='0'&&ch<='9'; ch=nc())x=x*10+ch-'0';
        if(sign)x=-x;
        return true;
    }
    template<class T,class... U>bool read(T& h,U&... t) {
        return read(h)&&read(t...);
    }
#undef OUT_SIZE
#undef BUF_SIZE
};
using namespace std;
using namespace FastIO;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int INF = 0x3f3f3f3f;
const int N = 1e6+10;

struct node {
    int ls,rs,ma,id;
    void clear() {
        ls=0;
        rs=0;
        ma=0;
        id=0;
    }
} tree[N * 10];

int ans[N],dep[N];
int root[N],cnt,st[N * 10],top;
vector<int>e[N];

void pp(int x) {
    int ls=tree[x].ls;
    int rs=tree[x].rs;
    if(tree[ls].ma>=tree[rs].ma) {
        tree[x].id=tree[ls].id;
        tree[x].ma=tree[ls].ma;
        return ;
    } else {
        tree[x].id=tree[rs].id;
        tree[x].ma=tree[rs].ma;
        return ;
    }
}

int newnode() {
    if(top) return st[top--];
    else return ++cnt;
}

void ins(int &x,int l,int r,int pos) {
    if(!x) x=newnode();
    if(l==r) {
        tree[x].ma++;
        tree[x].id=l;
        return ;
    }
    int mid=l+r>>1;
    if(pos<=mid) ins(tree[x].ls,l,mid,pos);
    else ins(tree[x].rs,mid+1,r,pos);
    pp(x);
}

int merge(int x,int y,int l,int r) {
    if( !x || !y) return x?x:y;
    if(l==r) {
        tree[x].ma+=tree[y].ma;
        st[++top]=y;
        tree[y].clear();
        return x;
    }
    int mid=l+r>>1;
    tree[x].ls=merge(tree[x].ls,tree[y].ls,l,mid);
    tree[x].rs=merge(tree[x].rs,tree[y].rs,mid+1,r);
    pp(x);
    tree[y].clear();
    st[++top]=y;
    return x;
}

void dfs(int u,int f) {
    dep[u]=dep[f]+1;
    root[u]=++cnt;
    for(auto v:e[u]) {
        if(v==f) continue;
        dfs(v,u);
        root[u]=merge(root[u],root[v],1,N);
    }
    ins(root[u],1,N,dep[u]);
    ans[u]=tree[root[u]].id-dep[u];
}

int main() {

#ifdef xiaofan
    freopen("1.in","r",stdin);
    freopen("1.out","w",stdout);
#endif

    int n;
    read(n);
    for(int i=1; i<n; i++) {
        int u,v;
        read(u,v);
        e[u].pb(v);
        e[v].pb(u);
    }
    dfs(1,0);
    for(int i=1; i<=n; i++) printf("%d\n",ans[i]);




    return 0;
}