BZOJ1984: 月下“毛景树”

题目链接

区间加，区间修改，区间最大值。

【代码】

#include <cstdio>
#include <iostream>
#include <queue>
#include <vector>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <stack>
#define N 100005 
#define M 5005
#define INF 1e9
#define mod 1000000007
using namespace std;
typedef long long ll;
typedef pair<ll,ll> pa;

int read()
{
    int x=0,f=1;char ch=getchar();
    while(!isdigit(ch)){if(ch=='-') f=-1;ch=getchar();}
    while(isdigit(ch)){x=(x<<1)+(x<<3)+ch-'0';ch=getchar();}
    return x*f;
}

int n,m,cnt,ind;
int b[N<<1],p[N],nextedge[N<<1],w[N<<1];
int sz[N],son[N],fa[N],pos[N],ftree[N],top[N],deep[N],a[N];

class Seg_Tree{
    public:
        int l,r,mx,tag;
        bool flag;
}e[N<<2];

void Add(int x,int y,int z)
{
    cnt++;
    b[cnt]=y;
    nextedge[cnt]=p[x];
    p[x]=cnt;
    w[cnt]=z;
} 

void Anode(int x,int y,int z){
    Add(x,y,z);Add(y,x,z);
}

void Input_Init()
{
    n=read();
    for(int i=1;i<n;i++) 
    {
        static int x,y,z;
        x=read(),y=read(),z=read();
        Anode(x,y,z);
    }
}

void Dfs(int x)
{
    sz[x]=1;
    for(int i=p[x];i;i=nextedge[i])
    {
        int v=b[i];
        if(v==fa[x]) continue;
        deep[v]=deep[x]+1;fa[v]=x;
        Dfs(v);sz[x]+=sz[v];
        son[x]=sz[son[x]]>sz[v]?son[x]:v;
    }
}

void dfs(int x,int root)
{
    pos[x]=++ind;ftree[pos[x]]=x;top[x]=root;
    if(!son[x]) return;
    dfs(son[x],root);
    for(int i=p[x];i;i=nextedge[i])
    {
        int v=b[i];
        if(v==fa[x]||v==son[x]) continue;
        dfs(v,v);
    }
}

void Edge_To_Node()
{
    for(int i=1;i<=cnt;i+=2)
    {
        int x=b[i],y=b[i+1];
        if(deep[x]<deep[y]) swap(x,y);
        a[x]=w[i];
    }
}

void pushup(int p){
    e[p].mx=max(e[p<<1].mx,e[p<<1|1].mx);
}

void pushdown(int p)
{
    if(e[p].flag)
    {
        e[p<<1].flag=1,e[p<<1|1].flag=1;
        e[p<<1].mx=e[p<<1|1].mx=e[p].mx;
        e[p<<1].tag=e[p<<1|1].tag=e[p].flag=0;
    } 
    if(e[p].tag)
    {
        if(!e[p<<1].flag) e[p<<1].tag+=e[p].tag;
        if(!e[p<<1|1].flag) e[p<<1|1].tag+=e[p].tag;
        e[p<<1].mx+=e[p].tag;e[p<<1|1].mx+=e[p].tag;
        e[p].tag=0;
    }
}

void Build(int p,int l,int r)
{
    e[p].l=l,e[p].r=r;
    if(l==r)
    {
        e[p].mx=a[ftree[l]];
        return;
    }
    int mid=l+r>>1;
    Build(p<<1,l,mid);Build(p<<1|1,mid+1,r);
    pushup(p);
}

void Pre_Work()
{
    Dfs(1);dfs(1,1);
    Edge_To_Node();Build(1,1,n);
}

int Query_Max(int p,int x,int y)
{
    int l=e[p].l,r=e[p].r,mid=l+r>>1;
    if(l^r) pushdown(p);
    if(l==x&&y==r) return e[p].mx;
    if(y<=mid) return Query_Max(p<<1,x,y);
    if(x>mid) return Query_Max(p<<1|1,x,y);
    return max(Query_Max(p<<1,x,mid),Query_Max(p<<1|1,mid+1,y));
}

void Solve_Max(int x,int y)
{
    int fx=top[x],fy=top[y];
    int rtn=-INF;
    while(fx!=fy)
    {
        if(deep[fx]<deep[fy]) swap(x,y),swap(fx,fy);
        rtn=max(rtn,Query_Max(1,pos[fx],pos[x]));
        x=fa[fx],fx=top[x];
    }
    if(deep[x]<deep[y]) swap(x,y);
    if(x!=y) rtn=max(rtn,Query_Max(1,pos[y]+1,pos[x]));
    printf("%d\n",rtn);
}

void Cover(int p,int x,int y,int z)
{
    int l=e[p].l,r=e[p].r,mid=l+r>>1;
    if(l^r) pushdown(p);
    if(l==x&&y==r)
    {
        e[p].flag=1;e[p].mx=z;
        return;
    }
    if(y<=mid) Cover(p<<1,x,y,z);
    else if(x>mid) Cover(p<<1|1,x,y,z);
    else Cover(p<<1,x,mid,z),Cover(p<<1|1,mid+1,y,z);
    pushup(p);
}

void Solve_Cover(int x,int y,int z)
{
    int fx=top[x],fy=top[y];
    while(fx!=fy)
    {
        if(deep[fx]<deep[fy]) swap(x,y),swap(fx,fy);
        Cover(1,pos[fx],pos[x],z);
        x=fa[fx],fx=top[x];
    }
    if(x==y) return;
    if(deep[x]<deep[y]) swap(x,y);
    Cover(1,pos[y]+1,pos[x],z);
}

void Solve_Change(int x,int y)
{
    int xx=b[x<<1],yy=b[(x<<1)-1];
    Solve_Cover(xx,yy,y);
}

void Increase(int p,int x,int y,int z)
{
    int l=e[p].l,r=e[p].r,mid=l+r>>1;
    if(l^r) pushdown(p);
    if(l==x&&y==r)
    {
        e[p].mx+=z;e[p].tag=z;
        return;
    }
    if(y<=mid) Increase(p<<1,x,y,z);
    else if(x>mid) Increase(p<<1|1,x,y,z);
    else Increase(p<<1,x,mid,z),Increase(p<<1|1,mid+1,y,z);
    pushup(p);
}

void Solve_Add(int x,int y,int z)
{
    int fx=top[x],fy=top[y];
    while(fx!=fy)
    {
        if(deep[fx]<deep[fy]) swap(x,y),swap(fx,fy);
        Increase(1,pos[fx],pos[x],z);
        x=fa[fx],fx=top[x];
    }
    if(x==y) return;
    if(deep[x]<deep[y]) swap(x,y);
    Increase(1,pos[y]+1,pos[x],z);
}

void Solve()
{
    while(true)
    {
        char ch[10];int x,y;
        scanf("%s",ch);if(ch[0]=='S') break;
        x=read(),y=read();
        if(ch[0]=='M') Solve_Max(x,y);
        else if(ch[1]=='o') Solve_Cover(x,y,read());
        else if(ch[1]=='h') Solve_Change(x,y);
        else Solve_Add(x,y,read());
    }
}

int main()
{
    Input_Init();
    Pre_Work();
    Solve();
    return 0;
}