luogu P4115 Qtree4

Posted 2020-11-21 sssy

题目链接

luogu P4115 Qtree4

题解

和上一题一样.同样三个堆.就是带权，用边权替换深度就好
为什么要单独写这个题解呢，因为我卡常卡了一天....据说树剖比rmq快？ 在第24次AC
同样也有更有做法

代码

#include<queue> 
#include<cstdio>
#include<cctype> 
#include<algorithm>


/*char ch;
char buf[100000],*p1 = buf,*p2 = buf;
int F = 1;
#define nc() 
    p1 == p2 && (p2 = (p1 = buf) + fread(buf,1,100000,stdin),p1 == p2) ? EOF :*p1 ++;
#define read(x)  
    x = 0;ch = nc();F = 1; 
    while(!isdigit(ch)) { if (ch == '-') F = -1; ch = nc();}
    while(isdigit(ch))x = x*10+ch - '0',ch = nc();
    x *= F;
    */


#define gc() (SS==TT&&(TT=(SS=IN)+fread(IN,1,MAXIN,stdin),SS==TT)?EOF:*SS++)
const int MAXIN=3e5;
char IN[MAXIN],*SS=IN,*TT=IN;
#define gc() (SS==TT&&(TT=(SS=IN)+fread(IN,1,MAXIN,stdin),SS==TT)?EOF:*SS++) 
inline int read() {
    int now=0,f=1;register char c=gc();
    for(;!isdigit(c);c=gc()) if(c=='-') f=-1;
    for(;isdigit(c);now=now*10+c-'0',c=gc());
    return now*f;
} 

#define INF 998244353 
const int maxn = 100007;  

int son[maxn],f[maxn],mn[maxn << 1][25],root,tot; 
struct node { 
    int u,v,next,w; 
} edge[maxn << 1]; 
int head[maxn],num = 0;
inline void add_edge(int u,int v,int w) { 
    edge[++ num].v = v;edge[num].next = head[u];head[u] = num;
    edge[num].w = w; 
}  
int n; 
int lg[maxn << 1],dfn;// = 0; 
bool col[maxn]; 

struct Heap { 
    std::priority_queue<int>A,B;
    inline void push(int x) { A.push(x); } 
    inline void erase(int x) { B.push(x); } 
    inline void pop() { while(B.size() && A.top() == B.top())  A.pop(),B.pop(); A.pop();  } 
    inline int top() { 
        while(B.size() && A.top() == B.top()) A.pop(),B.pop(); 
        return A.top(); 
    } 
    inline int size() { return A.size() - B.size();  } 
    int retop() { if(size() < 2) return 0;int x = top();pop();int ret = top();push(x);return ret;} 
} b[maxn],c[maxn],ans;
inline void insert(Heap &s) {if(s.size() > 1)ans.push(s.top() + s.retop());} 
inline void dele(Heap &s) {if(s.size() > 1) ans.erase(s.top() + s.retop());} 

int pos[maxn],Dis[maxn]; 
int id[maxn],tm;  

void dfs_rmq (int x,int fa) { 
    int t = ++ tm; mn[pos[x] = ++ dfn][0] = tm,id[t] = x; 
    for(int i = head[x];i;i = edge[i].next) { 
        int v = edge[i].v; 
        if(v == fa)continue; 
        Dis[v] = Dis[x] + edge[i].w;
        dfs_rmq(v,x); 
        mn[++ dfn][0] = t; //访问完子树后加上Qwq
    } 
} 
inline int lca(int x,int y) { 
    x = pos[x];y = pos[y]; 
    if(y < x) std::swap(x,y); 
    int k = lg[y - x + 1]; 
    return id[std::min(mn[x][k],mn[y - (1 << k) + 1][k])]; 
} 
inline int dis(int x,int y) { 
    return Dis[x] + Dis[y] - 2 * Dis[lca(x,y)]; 
} 
bool vis[maxn];int fa[maxn]; 
void get_root(int x,int fa) { 
    son[x] = 1; f[x] = 0; 
    for(int i = head[x];i;i = edge[i].next) { 
        int v = edge[i].v; 
        if(v == fa || vis[v]) continue; 
        get_root(v,x); 
        son[x] += son[v];f[x] = std::max(f[x],son[v]); 
    } 
    f[x] = std::max(f[x],tot - son[x]); 
    if(f[x] < f[root]) root = x; 
} 
void get(int x,int Fa,int rt) { 
    b[root].push(dis(x,fa[root]));  
    for(int i = head[x];i;i = edge[i].next) { 
        int v = edge[i].v; if(v == Fa || vis[v]) continue;
        get(v,x,rt); 
    } 
} 
void build(int x,int Fa) { 
    fa[x] = Fa;vis[x] = 1; 
    c[x].push(0); 
    get(x,0,Fa); 
    for(int i = head[x];i;i = edge[i].next) {
        int v = edge[i].v;
        if(!vis[v] && v != Fa) { 
            tot = son[edge[i].v];root = 0;f[0] = INF; 
            get_root(edge[i].v,x);
            v = root; 
            build(root,x); 
            c[x].push(b[v].top());  
        }  
    }   
    insert(c[x]); 
} 
void turn(int x,bool type) { 
    dele(c[x]); 
    if(type) c[x].erase(0); 
    else c[x].push(0); 
    insert(c[x]);
    for(int i = x;i;i = fa[i]) {
        dele(c[fa[i]]); 
        //printf("%d ",i); 
        if(b[i].size()) c[fa[i]].erase(b[i].top()); 
        if(type)b[i].erase(dis(x,fa[i])); else b[i].push(dis(x,fa[i])); 
        if(b[i].size()) c[fa[i]].push(b[i].top()); 
        insert(c[fa[i]]); 
    } 
    //puts("");
} 

inline char get(){
    char c=gc();
    while(c!='A'&&c!='C') c=gc();
    return c;
} 
int main() { 
     n = read();  
     //read(n); 
     for(int u,v,w,i = 1;i < n;++ i) {  
        u = read(),v = read(),w = read();  
        //read(u);read(v);read(w); 
        add_edge(u,v,w);add_edge(v,u,w);  
    }  
    dfs_rmq(1,0);  
    for(int i = 2;i <= dfn;++ i) lg[i] = lg[i >> 1] + 1; 
    for(int i = 1;i <= lg[dfn];++ i) 
        for(int j = dfn - (1 << i - 1);j;-- j) 
            mn[j][i] = std::min(mn[j][i - 1],mn[j + (1 << i - 1)][i - 1]); 
    f[0] = INF; root = 0; tot = n; 
    get_root(1,0); 
    build(root,0); 
    //char opt[10]; 
    int Q = read(); 
    
    int sum = n; 
    for(int asd;Q --;) { 
        //scanf("%s",opt + 1); 
        if(get() == 'C') { 
            asd = read();//read(asd); 
            if(col[asd]) turn(asd,0), sum ++,col[asd] = 0; 
            else turn(asd,1),sum --,col[asd] = 1;
        } 
        else  { 
            if(sum == 1)puts("0"); 
            else if(!sum)puts("They have disappeared."); 
            else printf("%d
",std::max(0,ans.top())); 
        } 
    } 
    return 0; 
}