【SDOI2015】寻宝游戏

代码

（树链剖分）

#include<cstdio>
#include<set>
using namespace std;
typedef long long LL;

const int N = 1e5;
int top[N + 5] , dfn[N + 5] , rev[N + 5] , fa[N + 5] , size[N + 5] , son[N + 5] , dep[N + 5];
LL dis[N + 5] , ans , now;
int vis[N + 5] , h[N + 5] , n , m , tot = 1 , cnt;
struct node1{
	int to , nxt , w;
}e[(N << 1) + 5]; 
set<int> list;
set<int>::iterator it;

inline int read()
{
	char ch = getchar();
	int res = 0;
	for(; ch < '0' || ch > '9'; ch = getchar());
	for(; ch >= '0' && ch <= '9'; ch = getchar()) res = (res << 3) + (res << 1) + ch - '0';
	return res;
}

inline void add(int x , int y , int z)
{
	e[++tot].to = y;
	e[tot].w = z;
	e[tot].nxt = h[x];
	h[x] = tot;
}

inline void dfs1(int x , int f , int d)
{
	dep[x] = d;
	dfn[x] = ++cnt;
	rev[cnt] = x;
	fa[x] = f;
	size[x] = 1;
	for(register int i = h[x]; i; i = e[i].nxt)
	{
		int v = e[i].to;
		if (v == f) continue;
		dis[v] = dis[x] + 1LL * e[i].w; 
		dfs1(v , x , d + 1);
		size[x] += size[v];
		if (size[v] > size[son[x]]) son[x] = v;
	}
}

inline void dfs2(int x , int f , int t)
{
	top[x] = t;
	if (son[x] > 0) dfs2(son[x] , x , t);
	for(register int i = h[x]; i; i = e[i].nxt)
	{
		int v = e[i].to;
		if (v == f || v == son[x]) continue;
		dfs2(v , x , v);
	}
}

inline int query(int x , int y)
{
	int fx = top[x] , fy = top[y];
	while (fx != fy)
	{
		if (dep[fx] >= dep[fy]) x = fa[fx] , fx = top[x];
		else y = fa[fy] , fy = top[y];
	}
	if (dep[x] <= dep[y]) return x;
	return y;
}

inline LL ask(int x , int y)
{
	return dis[x] + dis[y] - 2 * dis[query(x , y)];
}

int main()
{
//	freopen("寻宝游戏.in" , "r" , stdin);
	n = read() , m = read();
	int x , y , z;
	for(register int i = 1; i < n; i++) 
	{
		x = read() , y = read() , z = read();
		add(x , y , z) , add(y , x , z);
	}
	dfs1(1 , 0 , 1) , dfs2(1 , 0 , 1);
	for(register int i = 1; i <= m; i++)
	{
		x = read();
		x = dfn[x];
		if (!vis[rev[x]]) list.insert(x);
		y = rev[(it = list.lower_bound(x)) == list.begin() ? *--list.end() : *--it];
		z = rev[(it = list.upper_bound(x)) == list.end() ? *list.begin() : *it];
		if (vis[rev[x]]) list.erase(x);
		x = rev[x];
		now = ask(y , x) + ask(x , z) - ask(y , z);
		if (!vis[x]) vis[x] = 1 , ans += now;
		else vis[x] = 0 , ans -= now;
		printf("%lld\n" , ans);
	}
}

（倍增）

#include<cstdio>
#include<set>
using namespace std;
typedef long long LL;

const int N = 1e5;
int top[N + 5] , dfn[N + 5] , rev[N + 5] , fa[N + 5] , size[N + 5] , son[N + 5] , dep[N + 5];
LL dis[N + 5] , ans , now;
int vis[N + 5] , h[N + 5] , n , m , tot = 1 , cnt , f[N + 5][30];
struct node1{
	int to , nxt , w;
}e[(N << 1) + 5]; 
set<int> list;
set<int>::iterator it;

inline int read()
{
	char ch = getchar();
	int res = 0;
	for(; ch < '0' || ch > '9'; ch = getchar());
	for(; ch >= '0' && ch <= '9'; ch = getchar()) res = (res << 3) + (res << 1) + ch - '0';
	return res;
}

inline void add(int x , int y , int z)
{
	e[++tot].to = y;
	e[tot].w = z;
	e[tot].nxt = h[x];
	h[x] = tot;
}

inline int dfs(int x , int fa)
{
	dfn[x] = ++cnt; 
	rev[cnt] = x;
	for(register int i = 1; i <= 25; i++)
	if (f[x][i - 1]) f[x][i] = f[f[x][i - 1]][i - 1];
	else break;
	for(register int i = h[x]; i; i = e[i].nxt)
	{
		int v = e[i].to;
		if (v == fa) continue;
		dis[v] = dis[x] + e[i].w; 
		dep[v] = dep[x] + 1 , f[v][0] = x , dfs(v , x);
	}
}

inline int LCA(int u , int v)
{
	if (dep[u] < dep[v]) swap(u , v);
	register int deep = dep[u] - dep[v];
	for(register int i = 0; i <= 25; i++)
	if ((1 << i) & deep) u = f[u][i];
	if (u == v) return u;
	for(register int i = 25; i >= 0; i--)
		if (f[u][i] != f[v][i]) u = f[u][i] , v = f[v][i];
	return f[u][0];
}

inline LL ask(int x , int y)
{
	return dis[x] + dis[y] - 2 * dis[LCA(x , y)];
}

int main()
{
//	freopen("寻宝游戏.in" , "r" , stdin);
	n = read() , m = read();
	int x , y , z;
	for(register int i = 1; i < n; i++) 
	{
		x = read() , y = read() , z = read();
		add(x , y , z) , add(y , x , z);
	}
	dfs(1 , 0);
	for(register int i = 1; i <= m; i++)
	{
		x = read();
		x = dfn[x];
		if (!vis[rev[x]]) list.insert(x);
		y = rev[(it = list.lower_bound(x)) == list.begin() ? *--list.end() : *--it];
		z = rev[(it = list.upper_bound(x)) == list.end() ? *list.begin() : *it];
		if (vis[rev[x]]) list.erase(x);
		x = rev[x];
		now = ask(y , x) + ask(x , z) - ask(y , z);
		if (!vis[x]) vis[x] = 1 , ans += now;
		else vis[x] = 0 , ans -= now;
		printf("%lld\n" , ans);
	}
}