uoj30【CF Round #278】Tourists(圆方树+树链剖分+可删除堆)

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• 学习了一波圆方树
• 学习了一波点分治
• 学习了一波可删除堆(巧用 ? STL)

传送门: Icefox_zhx

注意看代码看怎么构建圆方树的.

tips:tips:tips:圆方树内存记得开两倍

CODE

#include <vector>
#include <queue>
#include <cstdio>
#include <cctype>
#include <cstring>
#include <algorithm>
using namespace std;
typedef long long LL;
inline void read(int &num) {
	char ch; int flg=1; while(!isdigit(ch=getchar()))if(ch=='-')flg=-flg;
	for(num=0; isdigit(ch); num=num*10+ch-'0',ch=getchar()); num*=flg;
}
const int MAXN = 100005;
const int INF = 1e9;
int n, m, q, tot, w[MAXN], dfn[MAXN<<1], tmr, stk[MAXN], indx;
vector<int> e[MAXN];
struct Heap {
	priority_queue<int, vector<int>, greater<int> >A, B;
	inline void insert(int x) { A.push(x); }
	inline void erase(int x) { B.push(x); }
	inline int top() {
		while(!B.empty() && A.top() == B.top()) A.pop(), B.pop();
		return A.empty() ? INF : A.top();
	}
}W[MAXN];
int fir[MAXN<<1], to[MAXN<<2], nxt[MAXN<<2], cnt;
inline void add(int u, int v) {
	to[cnt] = v; nxt[cnt] = fir[u]; fir[u] = cnt++;
}
int tarjan(int u, int fa) {
	int lowu = dfn[u] = ++tmr;
	stk[++indx] = u;
	for(int v, lowv, i = 0, siz = e[u].size(); i < siz; ++i)
		if(!dfn[v=e[u][i]]) {
			lowu = min(lowu, lowv=tarjan(v, u));
			if(lowv >= dfn[u]) {
				fir[++tot] = -1;
				do {
					W[tot-n].insert(w[stk[indx]]), add(tot, stk[indx]);
				}while(stk[indx--] != v);
				add(u, tot);
			}
		}
		else if(v != fa) lowu = min(lowu, dfn[v]);
	return lowu;
}
int dep[MAXN<<1], fa[MAXN<<1], sz[MAXN<<1], top[MAXN<<1], son[MAXN<<1], seq[MAXN<<1];
void dfs(int u, int ff) {
	dep[u] = dep[fa[u]=ff] + (sz[u]=1);
	for(int v, i = fir[u]; ~i; i = nxt[i]) {
		dfs(v=to[i], u), sz[u] += sz[v];
		if(sz[v] > sz[son[u]]) son[u] = v;
	}
}
void dfs2(int u, int tp) {
	top[u] = tp; seq[dfn[u] = ++tmr] = u;
	if(son[u]) dfs2(son[u], tp);
	for(int v, i = fir[u]; ~i; i = nxt[i])
		if((v=to[i]) != son[u]) dfs2(v, v);
}
int mn[MAXN<<3];
inline void upd(int i) { mn[i] = min(mn[i<<1], mn[i<<1|1]); }
void build(int i, int l, int r) {
	if(l == r) { mn[i] = seq[l] <= n ? w[seq[l]] : W[seq[l]-n].top(); return; }
	int mid = (l + r) >> 1;
	build(i<<1, l, mid);
	build(i<<1|1, mid+1, r);
	upd(i);
}
void modify(int i, int l, int r, int x) {
	if(l == r) { mn[i] = seq[l] <= n ? w[seq[l]] : W[seq[l]-n].top(); return; }
	int mid = (l + r) >> 1;
	if(x <= mid) modify(i<<1, l, mid, x);
	else modify(i<<1|1, mid+1, r, x);
	upd(i);
}
int query(int i, int l, int r, int x, int y) {
	if(l == x && r == y) return mn[i];
	int mid = (l + r) >> 1;
	if(y <= mid) return query(i<<1, l, mid, x, y);
	else if(x > mid) return query(i<<1|1, mid+1, r, x, y);
	else return min(query(i<<1, l, mid, x, mid), query(i<<1|1, mid+1, r, mid+1, y));
}
inline int Min(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, query(1, 1, tot, dfn[top[x]], dfn[x]));
		x = fa[top[x]];
	}
	if(dfn[x] < dfn[y]) swap(x, y);
	res = min(res, query(1, 1, tot, dfn[y], dfn[x]));
	if(y > n) res = min(res, w[fa[y]]);
	return res;
}
int main() {
	read(n), read(m), read(q); tot = n;
	for(int i = 1; i <= n; ++i) fir[i] = -1, read(w[i]);
	for(int i = 1, x, y; i <= m; ++i)
		read(x), read(y), e[x].push_back(y), e[y].push_back(x);
	tarjan(1, 0); tmr = 0; dfs(1, 0); dfs2(1, 1);
	build(1, 1, tot);
	char s; int x, y;
	while(q--) {
		while(!isalpha(s=getchar()));
		read(x), read(y);
		if(s == 'C') {
			if(fa[x]) {
				W[fa[x]-n].erase(w[x]);
				W[fa[x]-n].insert(y);
				modify(1, 1, tot, dfn[fa[x]]);
			}
			w[x] = y;
			modify(1, 1, tot, dfn[x]);
		}
		else printf("%d\n", Min(x, y));
	}
}