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zc
2019-12-21 19:47:00
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先根据原来的边建树

一条新边(x,y)能影响的边有树上x \rightarrow y路径上的边

那么这道题就转化成了树剖+线段树维护最值

#include<bits/stdc++.h>
namespace ZDY{
    #pragma GCC optimize(3)
    #define il __inline__ __attribute__ ((always_inline))
    #define rg register
    #define ll long long
    #define ull unsigned long long
    #define db double
    #define sht short
    #define MB template <class T>il
    #define Fur(i,x,y) for(int i=x;i<=y;++i)
    #define Fdr(i,x,y) for(int i=x;i>=y;--i)
    #define fl(i,x) for(int i=head[x],to;to=e[i].to,i;i=e[i].nxt)
    #define clr(x,y) memset(x,y,sizeof(x))
    #define cpy(x,y) memcpy(x,y,sizeof(x))
    #define fin(s) freopen(s".in","r",stdin)
    #define fout(s) freopen(s".out","w",stdout)
    #define fcin ios::sync_with_stdio(false)
    #define l2(n) ((int)(log2(n)))
    #define inf 2122219134
    MB T ABS(T x){return x>0?x:-x;}
    MB T MAX(T x,T y){return x>y?x:y;}
    MB T MIN(T x,T y){return x<y?x:y;}
    MB T GCD(T x,T y){return y?GCD(y,x%y):x;}
    MB void SWAP(T &x,T &y){T t=x;x=y;y=t;}
}using namespace ZDY;using namespace std;
namespace IO{const char* ln="\n";const int str=1<<20;struct IN{char buf[str],*s,*t;bool _;IN():s(buf),t(buf),_(0){}il char gc(){return s==t&&((t=(s=buf)+fread(buf,1,str,stdin))==s)?EOF:(*s++);}IN&operator>>(char&ch){if(_)return *this;char c;while((c=gc())!=EOF&&isspace(c));if(c==EOF)_=1;else ch=c;return *this;}IN& operator>>(char* ch){clr(ch,0);if(_)return *this;char c;while((c=gc())!=EOF&&isspace(c));if(c==EOF)return _=1,*this;*ch=c;ch++;while((c=gc())!=EOF&&!isspace(c))*ch=c,ch++;if(c==EOF)_=1;return *this;}IN& operator>>(string& ch){if(_)return *this;char c;while((c=gc())!=EOF&&isspace(c));if(c==EOF)return _=1,*this;ch+=c;while((c=gc())!=EOF&&!isspace(c))ch+=c;if(c==EOF)_=1;return *this;}template<typename T>IN&operator>>(T&x){if(_)return *this;char c=gc();bool ff=0;while(c!=EOF&&(c<'0'||c>'9'))ff^=(c=='-'),c=gc();if(c==EOF){_=1;return *this;}x=0;while(c!=EOF&&'0'<=c&&c<='9')x=(x<<3)+(x<<1)+c-48,c=gc();if(c==EOF)_=1;if(ff)x=-x;return *this;}}in;struct OUT{char buf[str],*s,*t;OUT():s(buf),t(buf+str){}~OUT(){fwrite(buf,1,s-buf,stdout);}void pt(char c){(s==t)?(fwrite(s=buf,1,str,stdout),*s++=c):(*s++=c);}OUT&operator<<(const char*s){while(*s)pt(*s++);return *this;}OUT&operator<<(char*s){while(*s)pt(*s++);return *this;}OUT&operator<<(string s){for(int i=0;s[i];i++)pt(s[i]);return *this;}template<typename T>OUT&operator<<(T x){if(!x)return pt('0'),*this;if(x<0)pt('-'),x=-x;char a[30],t=0;while(x)a[t++]=x%10,x/=10;while(t--)pt(a[t]+'0');return *this;}}out;}using namespace IO;
#define N 50011
#define ls rt<<1
#define rs rt<<1|1
#define pu s[rt]=MIN(s[ls],s[rs])
int n,m;
int s[N<<2],laz[N<<2];
void pd(int rt){
    if(laz[rt]!=inf){
        s[ls]=MIN(s[ls],laz[rt]);
        s[rs]=MIN(s[rs],laz[rt]);
        laz[ls]=MIN(laz[ls],laz[rt]);
        laz[rs]=MIN(laz[rs],laz[rt]);
        laz[rt]=inf;
    }
}
void upd(int L,int R,int v,int l=1,int r=n,int rt=1){
    if(L<=l&&r<=R){
        s[rt]=MIN(s[rt],v);
        laz[rt]=MIN(laz[rt],v);
        return;
    }
    int m=(l+r)>>1;
    pd(rt);
    if(L<=m)upd(L,R,v,l,m,ls);
    if(R>m)upd(L,R,v,m+1,r,rs);
    pu;
}
int get(int x,int l=1,int r=n,int rt=1){
    if(l==r)return s[rt];
    int m=(l+r)>>1;
    pd(rt);
    if(x<=m)return get(x,l,m,ls);
    else return get(x,m+1,r,rs);
}
struct edge{
    int to,nxt,id;
}e[N*2];
int head[N],cnt=0;
void add(int x,int y,int id){
    e[++cnt].to=y;e[cnt].nxt=head[x];head[x]=cnt;
    e[cnt].id=id;
}
int siz[N],d[N],f[N],top[N],id[N],sz=0,pte[N];
void dfs(int x){
    siz[x]=1;
    fl(i,x)if(to!=f[x]){
        d[to]=d[x]+1;f[to]=x;pte[to]=e[i].id;
        dfs(to);
        siz[x]+=siz[to];
    }
}
void bt(int x,int tp){
    id[x]=++sz;top[x]=tp;int k=0;
    fl(i,x)if(to!=f[x]&&siz[to]>siz[k])k=to;
    if(!k)return;bt(k,tp);
    fl(i,x)if(!top[to])bt(to,to);
}
void ul(int x,int y,int v){
    while(top[x]!=top[y]){
        if(d[top[x]]<d[top[y]])SWAP(x,y);
        upd(id[top[x]],id[x],v);x=f[top[x]];
    }
    if(id[x]>id[y])SWAP(x,y);
    upd(id[x]+1,id[y],v);
}
int etp[N];
int main(){
    fin("in");
    in>>n>>m;
    int x,y,w;
    Fur(i,1,n-1){
        in>>x>>y;
        add(x,y,i);add(y,x,i);
    }

    dfs(1);bt(1,1);
    clr(laz,126);clr(s,126);
    Fur(i,1,m)
        in>>x>>y>>w,ul(x,y,w);

    Fur(i,2,n)etp[pte[i]]=i;
    Fur(i,1,n-1){
        int t=get(id[etp[i]]);
        if(t==inf)t=-1;
        out<<t<<ln;
    }
}
LG 4374 [USACO18OPEN]Disruption
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