bzoj 4515: 游戏 树链剖分+线段树

题目大意:

http://www.lydsy.com/JudgeOnline/problem.php?id=4515

题解:

先让我%一发lych大佬点我去看dalao的题解

讲的很详细.

这里纠正一个地方,lych大佬的式子中有一个\(a*(d[s]-d[x])+b=-a*d[x]+(b-a*d[s])\)

应该是\(a*(d[s]-d[x])+b = -a*d[x] + (b+a*d[s])\)

看来是大爷敲式子的时候敲错了...

除去这个就很完美啦

新get了线段树标记永久化的姿势

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
typedef long long ll;
template<typename T>inline void read(T &x){
	x=0;char ch;bool flag = false;
	while(ch=getchar(),ch<'!');if(ch == '-') ch=getchar(),flag = true;
	while(x=10*x+ch-'0',ch=getchar(),ch>'!');if(flag) x=-x;
}
const ll maxn = 210010;
const ll inf = 123456789123456789LL;
struct Edge{
	ll to,next;
	ll dis;
}G[maxn<<1];
ll head[maxn],cnt;
void add(ll u,ll v,ll d){
	G[++cnt].to = v;
	G[cnt].next = head[u];
	head[u] = cnt;
	G[cnt].dis = d;
}
ll son[maxn],siz[maxn],fa[maxn],top[maxn];
ll dfn[maxn],dfs_clock,num[maxn],dep[maxn];
ll d[maxn];
#define v G[i].to
void dfs(ll u){
	siz[u] = 1;
	for(ll i = head[u];i;i=G[i].next){
		if(v == fa[u]) continue;
		fa[v] = u;
		d[v] = d[u] + G[i].dis;
		dep[v] = dep[u] + 1;
		dfs(v);
		siz[u] += siz[v];
		if(siz[son[u]] < siz[v]) son[u] = v;
	}
}
void dfs(ll u,ll tp){
	top[u] = tp;
	dfn[u] = ++dfs_clock;
	num[dfs_clock] = u;
	if(son[u]) dfs(son[u],tp);
	for(ll i = head[u];i;i=G[i].next){
		if(v == fa[u] || v == son[u]) continue;
		dfs(v,v);
	}
}
#undef v
struct Node{
	ll k,b,minn;
	bool lazy;
	Node(){k=lazy=0;b = minn = inf;}
}T[maxn<<2];
ll K,B,L,R;ll n;
ll query(ll rt,ll l,ll r){
	if(L <= l && r <= R) return T[rt].minn;
	ll ret = inf;
	if(T[rt].lazy) ret = min(T[rt].k*d[num[max(L,l)]],T[rt].k*d[num[min(R,r)]]) + T[rt].b;
	ll mid = l+r >> 1;
	if(L <= mid) ret = min(ret,query(rt<<1,l,mid));
	if(R >  mid) ret = min(ret,query(rt<<1|1,mid+1,r));
	return ret;
}
inline ll query(ll l,ll r){
	if(l > r) swap(l,r);
	L = l;R = r;

	return query(1,1,n);
}
void update(ll rt,ll l,ll r,ll K,ll B){
	if(T[rt].lazy == 0){
		T[rt].k = K;T[rt].b = B;T[rt].lazy = 1;
		if(l < r) T[rt].minn = min(T[rt<<1].minn,T[rt<<1|1].minn);
		T[rt].minn = min(T[rt].minn,min(T[rt].k*d[num[l]],T[rt].k*d[num[r]])+T[rt].b);
		return;
	}
	ll mid = l+r >> 1;
	ll y1 = K*d[num[r]] + B;
	ll y2 = T[rt].k*d[num[r]] + T[rt].b;
	ll y3 = K*d[num[l]] + B;
	ll y4 = T[rt].k*d[num[l]] + T[rt].b;
	if(y3 <= y4 && y1 <= y2) T[rt].k = K,T[rt].b = B;
	else if(y3 >= y4 && y1 >= y2) return;
	else if(T[rt].k > K){
		ll x = (B-T[rt].b)/(T[rt].k-K) + 1;
		if(x <= d[num[mid]]){
			swap(T[rt].b,B);swap(T[rt].k,K);
			update(rt<<1,l,mid,K,B);
		}else update(rt<<1|1,mid+1,r,K,B);
	}else{
		ll x = (T[rt].b - B - 1)/(K - T[rt].k);
		if(x > d[num[mid]]){
			swap(T[rt].b,B);swap(T[rt].k,K);
			update(rt<<1|1,mid+1,r,K,B);
		}else update(rt<<1,l,mid,K,B);
	}
	if(l < r) T[rt].minn = min(T[rt<<1].minn,T[rt<<1|1].minn);
	if(T[rt].lazy) T[rt].minn = min(T[rt].minn,
		min(T[rt].k*d[num[l]],T[rt].k*d[num[r]])+T[rt].b);
}
void ins(ll rt,ll l,ll r){
	if(L <= l && r <= R){
		update(rt,l,r,K,B);return;
	}
	ll mid = l+r >> 1;
	if(L <= mid) ins(rt<<1,l,mid);
	if(R >  mid) ins(rt<<1|1,mid+1,r);
	T[rt].minn = min(T[rt<<1].minn,T[rt<<1|1].minn);
	if(T[rt].lazy) T[rt].minn = min(T[rt].minn,
		min(T[rt].k*d[num[l]],T[rt].k*d[num[r]])+T[rt].b);
}
inline void ins(ll l,ll r){
	if(l > r) swap(l,r);
	L=l;R=r;ins(1,1,n);
}
inline ll lca(ll u,ll v){
	while(top[u] != top[v]){
		if(dep[top[u]] < dep[top[v]]) swap(u,v);
		u = fa[top[u]];
	}return dep[u] < dep[v] ? u : v;
}
inline void insert(ll u,ll v,ll a,ll b){
	ll rt = lca(u,v);
	K = -a;B = b+a*d[u];
	while(top[u] != top[rt]){
		ins(dfn[top[u]],dfn[u]);
		u = fa[top[u]];
	}ins(dfn[rt],dfn[u]);
	K = a;B -= (d[rt]<<1)*a;
	while(top[v] != top[rt]){
		ins(dfn[top[v]],dfn[v]);
		v = fa[top[v]];
	}ins(dfn[rt],dfn[v]);
}
inline ll query_all(ll u,ll v){
	ll ret = inf;
	while(top[u] != top[v]){
		if(dep[top[u]] < dep[top[v]]) swap(u,v);
		ret = min(ret,query(dfn[top[u]],dfn[u]));
		u = fa[top[u]];
	}if(dep[u] < dep[v]) swap(u,v);
	ret = min(ret,query(dfn[v],dfn[u]));
	return ret;
}
int main(){
	ll m;read(n);read(m);
	for(ll i=1,u,v;i<n;++i){ll d;
		read(u);read(v);read(d);
		add(u,v,d);add(v,u,d);
	}dfs(1);dfs(1,1);
	ll op,s,t;ll a,b;
	while(m--){
		read(op);read(s);read(t);
		if(op == 1){
			read(a);read(b);
			insert(s,t,a,b);
		}else{
			printf("%lld\n",query_all(s,t));
		}
	}
	getchar();getchar();
	return 0;
}

我能说我从昨天下午调到了今天上午,调了6个小时吗?