Title Description
Le Ray loyal to travel, this time he came to the city of T. T City is a water city, a total of N spots, will be connected by a bridge between some attractions. For the convenience of tourists arrive each attraction but in order to save costs, there is only one path between any two T City attractions. In other words, T city only N - 1 bridges.
Ray found that the bridge can see some beautiful scenery, people feel good, but some muddy narrow bridge, annoying. So he gave every seat define a bridge valence w, that is to say, Ray after the bridge will increase the pleasure of w, which may be positive or may be negative. Sometimes, Ray look the same bridge mood will change.
Now, Ray wants you to help him calculate the total pleasure of the attractions that can be obtained from u to v attractions. Sometimes, he wants to know the minimum degree of pleasure maximum pleasure a certain degree the most beautiful bridge on the road to offer, or certain of the worst road bridge provided.
Resolve
Bare tree section title, but to little attention to the maintenance of opposite number, negatives make a positive, and a range of flipping.
Reference Code
#include<cstdio>
#include<iostream>
#include<cmath>
#include<cstring>
#include<ctime>
#include<cstdlib>
#include<algorithm>
#include<queue>
#include<set>
#include<map>
#define N 100010
#define INF 0x3f3f3f3f
using namespace std;
inline int read()
{
int f=1,x=0;char c=getchar();
while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();}
while(c>='0'&&c<='9'){x=x*10+c-'0';c=getchar();}
return x*f;
}
struct rec{
int next,ver,edge;
}g[N<<1];
int head[N],tot,n,cnt,m;
struct tree{
int l,r;
int max,min,sum,rem;
}t[N<<2];
inline void add(int x,int y,int val)
{
g[++tot].ver=y,g[tot].edge=val;
g[tot].next=head[x],head[x]=tot;
}
int top[N],size[N],id[N],dep[N],son[N],fa[N],w[N],wt[N];
struct node{
int u,v;
}a[N];
inline void pushup(int p)
{
t[p].sum=t[p<<1].sum+t[p<<1|1].sum;
t[p].max=max(t[p<<1].max,t[p<<1|1].max);
t[p].min=min(t[p<<1].min,t[p<<1|1].min);
}
inline void pushdown(int p)
{
if(t[p].rem){
t[p<<1].rem^=1;t[p<<1|1].rem^=1;
t[p<<1].sum*=-1;t[p<<1|1].sum*=-1;
t[p<<1].max*=-1;t[p<<1].min*=-1;
t[p<<1|1].max*=-1;t[p<<1|1].min*=-1;
swap(t[p<<1].max,t[p<<1].min);swap(t[p<<1|1].max,t[p<<1|1].min);
t[p].rem^=1;
}
}
inline void build(int p,int l,int r)
{
t[p].l=l,t[p].r=r;t[p].max=-INF,t[p].min=INF;
if(l==r){t[p].sum=t[p].max=t[p].min=w[l];return;}
int mid=(l+r)>>1;
build(p<<1,l,mid);
build(p<<1|1,mid+1,r);
pushup(p);
}
inline void change(int p,int x,int val)
{
if(t[p].l==t[p].r&&t[p].l==x){
t[p].sum=t[p].max=t[p].min=val;
t[p].rem=0;
return;
}
pushdown(p);
int mid=(t[p].l+t[p].r)>>1;
if(x<=mid) change(p<<1,x,val);
else change(p<<1|1,x,val);
pushup(p);
}
inline void mirror(int p,int l,int r)
{
if(l<=t[p].l&&t[p].r<=r){
t[p].sum*=-1;
t[p].max*=-1;t[p].min*=-1;
swap(t[p].max,t[p].min);
t[p].rem^=1;
return;
}
pushdown(p);
int mid=(t[p].l+t[p].r)>>1;
if(l<=mid) mirror(p<<1,l,r);
if(r>mid) mirror(p<<1|1,l,r);
pushup(p);
}
inline int Sum(int p,int l,int r)
{
if(l<=t[p].l&&t[p].r<=r) return t[p].sum;
pushdown(p);
int mid=(t[p].l+t[p].r)>>1;
int val=0;
if(l<=mid) val+=Sum(p<<1,l,r);
if(r>mid) val+=Sum(p<<1|1,l,r);
return val;
}
inline int Max(int p,int l,int r)
{
if(l<=t[p].l&&t[p].r<=r) return t[p].max;
pushdown(p);
int mid=(t[p].l+t[p].r)>>1;
int val=-INF;
if(l<=mid) val=max(val,Max(p<<1,l,r));
if(r>mid) val=max(val,Max(p<<1|1,l,r));
return val;
}
inline int Min(int p,int l,int r)
{
if(l<=t[p].l&&t[p].r<=r) return t[p].min;
pushdown(p);
int mid=(t[p].l+t[p].r)>>1;
int val=INF;
if(l<=mid) val=min(val,Min(p<<1,l,r));
if(r>mid) val=min(val,Min(p<<1|1,l,r));
return val;
}
inline void dfs1(int x,int f,int deep)
{
size[x]=1,fa[x]=f,dep[x]=deep;
int maxson=-1;
for(int i=head[x];i;i=g[i].next){
int y=g[i].ver,z=g[i].edge;
if(y==f) continue;
dfs1(y,x,deep+1);
wt[y]=z;
size[x]+=size[y];
if(maxson<size[y]) maxson=size[y],son[x]=y;
}
}
inline void dfs2(int x,int topf)
{
id[x]=++cnt,w[cnt]=wt[x],top[x]=topf;
if(!son[x]) return;
dfs2(son[x],topf);
for(int i=head[x];i;i=g[i].next){
int y=g[i].ver;
if(y==fa[x]||y==son[x]) continue;
dfs2(y,y);
}
}
inline void Mirror(int x,int y)
{
while(top[x]!=top[y]){
if(dep[top[x]]<dep[top[y]]) swap(x,y);
mirror(1,id[top[x]],id[x]);
x=fa[top[x]];
}
if(dep[x]>dep[y]) swap(x,y);
mirror(1,id[x]+1,id[y]);
}
inline int Maxx(int x,int y)
{
int res=-INF;
while(top[x]!=top[y]){
if(dep[top[x]]<dep[top[y]]) swap(x,y);
res=max(res,Max(1,id[top[x]],id[x]));
x=fa[top[x]];
}
if(dep[x]>dep[y]) swap(x,y);
res=max(res,Max(1,id[x]+1,id[y]));
return res;
}
inline int Minn(int x,int y)
{
int res=INF;
while(top[x]!=top[y]){
if(dep[top[x]]<dep[top[y]]) swap(x,y);
res=min(res,Min(1,id[top[x]],id[x]));
x=fa[top[x]];
}
if(dep[x]>dep[y]) swap(x,y);
res=min(res,Min(1,id[x]+1,id[y]));
return res;
}
inline int SUM(int x,int y)
{
int res=0;
while(top[x]!=top[y]){
if(dep[top[x]]<dep[top[y]]) swap(x,y);
res+=Sum(1,id[top[x]],id[x]);
x=fa[top[x]];
}
if(dep[x]>dep[y]) swap(x,y);
res+=Sum(1,id[x]+1,id[y]);
return res;
}
int main()
{
n=read();
for(int i=1;i<n;++i){
a[i].u=read(),a[i].v=read();
a[i].u++,a[i].v++;
int z=read();
add(a[i].u,a[i].v,z),add(a[i].v,a[i].u,z);
}
dfs1(1,0,1);
dfs2(1,1);
build(1,1,n);
m=read();
while(m--){
char op[10];
scanf("%s",op);
int x=read(),y=read();
if(op[0]=='S'){
x++,y++;
printf("%d\n",SUM(x,y));
}
if(op[0]=='N'){
x++,y++;
Mirror(x,y);
}
if(op[0]=='C'){
if(fa[a[x].u]==a[x].v) change(1,id[a[x].u],y);
if(fa[a[x].v]==a[x].u) change(1,id[a[x].v],y);
}
if(op[0]=='M'){
x++,y++;
if(op[1]=='A'){
printf("%d\n",Maxx(x,y));
}
else printf("%d\n",Minn(x,y));
}
}
return 0;
}