Hdu5893树链剖分（2016沈阳网络赛B）
在另一道题目的基础上的改编题目，只不过把点权改成了边权，因为在边上，所以在合并区间时候注意lca点处的答案不需要合并。写法很多，当时这个check一直没想明白，wa了9发，到最后算是绝杀了吧。树链剖分题目还是完全理解概念以后再碰吧，否则会wa的很惨的。不过这个算法算是很精髓的了，可以解决大部分树链问题。
//#include <bits\stdc++.h>
//#pragma comment(linker,"/STACK:102400000,102400000")
#include <cstdio>
#include <cstring>
#include <iostream>
#include <cstdlib>
#include <vector>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <ctime>
#include <cmath>
#include <algorithm>
#include <bitset>
#define sqr(x) ((x)*(x))
#define lson (p<<1)
#define rson (lson | 1)
#define EPS 1e-10
#define PII pair<int,int>
#define PLI pair<LL,int>
#define PLL pair<LL,LL>
#define PIL pair<int,LL>
#define mk(x,y) make_pair(x,y)
#define lowbit(x) (x&(-x))
#define FRfreopen("in.txt","r",stdin)
#define FWfreopen("out.txt","w",stdout)
using namespace std;
template <class T>
inline voidread(T &x){char c = getchar(); x =0;while(!isdigit(c))c = getchar();while(isdigit(c)){x=x*10+ c-'0';c = getchar();}}
template <class T>
inline voidrd(T &res) {static char ch; bool sgn =false;while (ch = getchar(), ch < '0' ||ch > '9') if (ch == '-') sgn = true;
res = ch - 48;while (ch = getchar(),ch >= '0' && ch <= '9') res =res * 10 + ch - 48; res = sgn ? -res: res;}
template <class T> void Out(T a) { if(a < 0){putchar('-');a= -a;}if(a >= 10)Out(a / 10);putchar(a% 10 + '0'); }
typedef long long LL;
#define INT __int64
#define L(x) (x * 2)
#define R(x) (x * 2 + 1)
const int MX= 1e5+10;
const int N= 1e5+10;
const int oo= -0x3f3f3f3f;
int n ,m,idx ,num ;
int head[MX],ti[MX] ,top[MX] ,dep[MX] ,siz[MX],son[MX] ,father[MX] ,g[MX] ;
struct Edge
{
int v ,next;
}E[MX*2];
void addedge(intu ,int v)
{
E[num].v= v ; E[num].next = head[u] ;head[u] = num++ ;
E[num].v= u ; E[num].next = head[v] ;head[v] = num++ ;
}
voiddfs_find(int u ,int fa)
{
dep[u] = dep[fa] + 1 ;
siz[u] = 1 ;
son[u] = 0 ;
father[u] = fa ;
for(int i = head[u] ;i!= -1 ;i = E[i].next)
{
int v = E[i].v ;
if(v == fa) continue ;
dfs_find(v ,u) ;
siz[u] += siz[v];
if(siz[son[u]] < siz[v]) son[u] = v ;
}
}
voiddfs_time(int u ,int fa)
{
ti[u] = idx++;
top[u] = fa ;
if(son[u]) dfs_time(son[u] ,top[u]);
for(int i = head[u] ;i!= -1 ;i = E[i].next)
{
int v = E[i].v ;
if(v == father[u] || v== son[u]) continue;
dfs_time(v ,v) ;
}
}
struct node
{
int le ,rt ,lc ,rc ,num,add ;
}T[MX<<2];
void build(intx ,int le ,int rt)
{
T[x].le= le ; T[x].rt = rt ;
T[x].lc= T[x].rc = T[x].add = oo;
T[x].num= 0 ;
if(le == rt) return ;
int Mid = (le + rt)>>1;
build(L(x) ,le ,Mid) ;
build(R(x) ,Mid + 1 ,rt) ;
}
voidpush_down(int x)
{
if(T[x].add != oo)
{
T[L(x)].lc = T[L(x)].rc= T[L(x)].add = T[x].add ;T[L(x)].num = 1 ;
T[R(x)].lc = T[R(x)].rc= T[R(x)].add = T[x].add ;T[R(x)].num = 1 ;
T[x].add = oo;
}
}
void push_up(intx)
{
T[x].num= T[L(x)].num + T[R(x)].num;
if(T[L(x)].rc ==T[R(x)].lc) T[x].num -- ;
T[x].lc= T[L(x)].lc ; T[x].rc = T[R(x)].rc;
}
void update(intx ,int le ,int rt ,int w)
{
if(T[x].le == le&& T[x].rt == rt)
{
T[x].add = w ; T[x].lc =w ; T[x].rc = w ; T[x].num= 1;
return ;
}
push_down(x);
int Mid = (T[x].le +T[x].rt)>>1;
if(le > Mid) update(R(x) ,le ,rt,w) ;
else if(rt <= Mid) update(L(x) ,le ,rt,w) ;
else
{
update(L(x) ,le ,Mid ,w) ;
update(R(x) ,Mid+1 ,rt ,w);
}
push_up(x) ;
}
int Query(intx ,int le ,int rt)
{
if(T[x].le == le&& T[x].rt == rt) return T[x].num;
int Mid = (T[x].le +T[x].rt)>>1 ;
push_down(x) ;
if(le > Mid) return Query(R(x) ,le ,rt) ;
else if(rt <= Mid) return Query(L(x) ,le ,rt);
else
{
int mx = 0 ;
if(T[L(x)].rc ==T[R(x)].lc) mx = -1;
return Query(L(x) ,le ,Mid) + Query(R(x),Mid+1 ,rt) + mx ;
}
push_up(x) ;
}
intQuerynode(int x ,int pos)
{
if(T[x].le == T[x].rt)return T[x].lc ;
int Mid = (T[x].le +T[x].rt)>>1 ;
push_down(x) ;
if(pos <= Mid) return Querynode(L(x) ,pos) ;
else return Querynode(R(x),pos) ;
push_up(x) ;
}
void LCAC(intu ,int v ,int w)
{
while(top[u] != top[v])
{
if(dep[top[u]] < dep[top[v]])swap(u ,v) ;
update(1 ,ti[top[u]],ti[u] ,w) ;
u = father[top[u]] ;
}
if(u == v) return;
if(dep[u] > dep[v])swap(u ,v) ;
update(1 ,ti[son[u]] ,ti[v],w) ;
}
int LCAQ(intu ,int v)
{
if(u == v) return 0;
int ans = 0;
while(top[u] != top[v])
{
if(father[u] == father[v])
{
ans += Query(1 ,ti[u] ,ti[u])+ Query(1 ,ti[v] ,ti[v]);
if(Querynode(1,ti[u]) == Querynode(1 ,ti[v] ))ans--;
returnans;
}
if(dep[top[u]] < dep[top[v]])swap(u ,v) ;
ans += Query(1 ,ti[top[u]] ,ti[u]);
int x = father[top[u]];
if(top[x] == top[v])
{
if(dep[x]<= dep[v])
{
if(x== v) return ans;
if(Querynode(1 ,ti[top[u]]) == Querynode(1,ti[ son[x] ] ) ) ans--;
u = father[top[u]];
break;
}
}
if(Querynode(1 ,ti[top[u]])== Querynode(1 ,ti[father[top[u]]]))ans--;
u = father[top[u]] ;
}
if(u == v) return ans;
if(dep[u] > dep[v])swap(u ,v) ;
ans += Query(1 ,ti[son[u]] ,ti[v]);
return ans ;
}
struct rp
{
int x,y,w;
}f[N];
char s[110];
int main()
{
while(~scanf("%d%d",&n,&m))
{
int u,v,w ;
num = 0;
memset(head ,-1 ,sizeof(head)) ;
for(int i = 1 ;i < n; ++i)
{
scanf("%d%d%d" ,&u ,&v, &w) ;
addedge(u ,v);
f[i].x = u;
f[i].y = v;
f[i].w = w;
}
dep[1] = siz[0] = 0 ;
dfs_find(1,1);
father[1] = 0;
idx = 1;
dfs_time(1,1);
build(1 ,1 ,idx);
for(int i = 1 ;i < n; ++i)
{
if(dep[f[i].x]>dep[f[i].y]) swap(f[i].x,f[i].y);
update(1 ,ti[f[i].y],ti[f[i].y] ,f[i].w) ;
}
for(int i = 0 ;i < m; ++i)
{
scanf("%s",s);
scanf("%d%d",&u ,&v);
if(s[0]== 'C')
{
scanf("%d",&w);
if(u>n|| v>n) continue;
LCAC(u,v,w);
} elseprintf("%d\n",(u>n || v>n)? 0 : LCAQ(u,v) );
}
}
return 0 ;
}
/*
9 3
1 2 2
2 3 1
1 7 2
1 4 2
3 5 2
3 6 1
5 8 2
5 9 3
Query 1 8
Change 2 6 3
Query 1 6
*/
