AC日记——[国家集训队2011]旅游(宋方睿) cogs 1867

[国家集训队2011]旅游(宋方睿)

思路：

　　树链剖分，边权转点权；

　　线段树维护三个东西，sum，max，min；

　　当一个区间变成相反数时，sum=-sum，max=-min，min=-max；

来，上代码：

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>

using namespace std;

#define maxn 100005
#define ll long long
#define INF 0x7fffffff

struct TreeNodeType {
    ll l,r,mi,ma,sum,mid,flag;
};
struct TreeNodeType tree[maxn<<];

ll n,m,E[maxn<<],V[maxn<<],W[maxn<<],cnt;
ll deep[maxn],ps[maxn],pe[maxn],head[maxn],X,ty;
ll f[maxn],id[maxn],ds[maxn],size[maxn],top[maxn];

inline void in(ll &now)
{
    ll if_z=;now=;
    char Cget=getchar();
    while(Cget>''||Cget<'')
    {
        if(Cget=='-') if_z=-;
        Cget=getchar();
    }
    while(Cget>=''&&Cget<='')
    {
        now=now*+Cget-'';
        Cget=getchar();
    }
    now*=if_z;
}

inline void edge_add(ll u,ll v,ll w)
{
    E[++cnt]=head[u],V[cnt]=v,W[cnt]=w,head[u]=cnt;
    E[++cnt]=head[v],V[cnt]=u,W[cnt]=w,head[v]=cnt;
}

void pre(ll now,ll fa)
{
    f[now]=fa,size[now]=;
    if(fa==-) deep[now]=;
    else deep[now]=deep[fa]+;
    for(ll i=head[now];i;i=E[i])
    {
        if(V[i]==fa) continue;
        pre(V[i],now),size[now]+=size[V[i]];
    }
}

void dfs(ll now,ll chain,ll dis)
{
    ll pos=n+,ww;
    top[now]=chain,id[now]=++cnt,ds[cnt]=dis;
    for(ll i=head[now];i;i=E[i])
    {
        if(V[i]==f[now]) continue;
        if(size[V[i]]>size[pos]) pos=V[i],ww=W[i];
    }
    if(pos==n+) return ;
    dfs(pos,chain,ww);
    for(ll i=head[now];i;i=E[i])
    {
        if(V[i]==pos||V[i]==f[now]) continue;
        dfs(V[i],V[i],W[i]);
    }
}

void tree_build(ll now,ll l,ll r)
{
    tree[now].l=l,tree[now].r=r;
    if(l==r)
    {
        tree[now].mi=ds[l];
        tree[now].ma=ds[l];
        tree[now].sum=ds[l];
        return ;
    }
    tree[now].mid=l+r>>;
    tree_build(now<<,l,tree[now].mid);
    tree_build(now<<|,tree[now].mid+,r);
    tree[now].sum=tree[now<<].sum+tree[now<<|].sum;
    tree[now].ma=max(tree[now<<].ma,tree[now<<|].ma);
    tree[now].mi=min(tree[now<<].mi,tree[now<<|].mi);
}

inline void tree_down(ll now)
{
    ll mii=tree[now<<].mi,maa=tree[now<<].ma;
    tree[now<<].ma=-mii,tree[now<<].mi=-maa;
    tree[now<<].sum=-tree[now<<].sum;
    mii=tree[now<<|].mi,maa=tree[now<<|].ma;
    tree[now<<|].mi=-maa,tree[now<<|].ma=-mii;
    tree[now<<|].sum=-tree[now<<|].sum;
    tree[now<<].flag=!tree[now<<].flag;
    tree[now<<|].flag=!tree[now<<|].flag;
    tree[now].flag=false;
}

void tree_query(ll now,ll l,ll r)
{
    if(tree[now].l==l&&tree[now].r==r)
    {
        if(ty==) X+=tree[now].sum;
        else if(ty==) X=max(X,tree[now].ma);
        else X=min(X,tree[now].mi);
        return ;
    }
    if(tree[now].flag) tree_down(now);
    if(l>tree[now].mid) tree_query(now<<|,l,r);
    else if(r<=tree[now].mid) tree_query(now<<,l,r);
    else tree_query(now<<,l,tree[now].mid),tree_query(now<<|,tree[now].mid+,r);
}

void tree_change(ll now,ll to)
{
    if(tree[now].l==tree[now].r)
    {
        tree[now].mi=X;
        tree[now].ma=X;
        tree[now].sum=X;
        return ;
    }
    if(tree[now].flag) tree_down(now);
    if(to<=tree[now].mid) tree_change(now<<,to);
    else tree_change(now<<|,to);
    tree[now].sum=tree[now<<].sum+tree[now<<|].sum;
    tree[now].ma=max(tree[now<<].ma,tree[now<<|].ma);
    tree[now].mi=min(tree[now<<].mi,tree[now<<|].mi);
}

void tree_change_(ll now,ll l,ll r)
{
    if(tree[now].l==l&&tree[now].r==r)
    {
        tree[now].flag=!tree[now].flag;
        ll mii=tree[now].mi,maa=tree[now].ma;
        tree[now].sum=-tree[now].sum;
        tree[now].ma=-mii,tree[now].mi=-maa;
        return ;
    }
    if(tree[now].flag) tree_down(now);
    if(l>tree[now].mid) tree_change_(now<<|,l,r);
    else if(r<=tree[now].mid) tree_change_(now<<,l,r);
    else tree_change_(now<<,l,tree[now].mid),tree_change_(now<<|,tree[now].mid+,r);
    tree[now].sum=tree[now<<].sum+tree[now<<|].sum;
    tree[now].ma=max(tree[now<<].ma,tree[now<<|].ma);
    tree[now].mi=min(tree[now<<].mi,tree[now<<|].mi);
}

void solve_change(ll x,ll y)
{
    while(top[x]!=top[y])
    {
        if(deep[top[x]]<deep[top[y]]) swap(x,y);
        tree_change_(,id[top[x]],id[x]);
        x=f[top[x]];
    }
    if(deep[x]>deep[y]) swap(x,y);
    if(x!=y) tree_change_(,id[x]+,id[y]);
}

void solve_query(ll x,ll y)
{
    while(top[x]!=top[y])
    {
        if(deep[top[x]]<deep[top[y]]) swap(x,y);
        tree_query(,id[top[x]],id[x]);
        x=f[top[x]];
    }
    if(deep[x]>deep[y]) swap(x,y);
    if(x!=y) tree_query(,id[x]+,id[y]);
}

int main()
{
    freopen("nt2011_travel.in","r",stdin);
    freopen("nt2011_travel.out","w",stdout);
    in(n);ll u,v,w;
    for(ll i=;i<n;i++)
    {
        in(u),in(v),in(w);
        edge_add(u,v,w);
        ps[i]=u,pe[i]=v;
    }
    cnt=,pre(,-),dfs(,,);
    tree_build(,,n);
    in(m);char ch[];
    while(m--)
    {
        scanf("%s",ch);in(u),in(v);
        if(ch[]=='N') solve_change(u,v);
        else if(ch[]=='C')
        {
            X=v;
            if(deep[ps[u]]>deep[pe[u]]) swap(ps[u],pe[u]);
            tree_change(,id[pe[u]]);
        }
        else if(ch[]=='S') ty=,X=,solve_query(u,v),printf("%lld\n",X);
        else if(ch[]=='M')
        {
            if(ch[]=='A') ty=,X=-INF,solve_query(u,v),printf("%lld\n",X);
            else ty=,X=INF,solve_query(u,v),printf("%lld\n",X);
        }
    }
    fclose(stdin),fclose(stdout);
    return ;
}