BZOJ 3551/3545: [ONTAK2010]Peaks加强版 (Kruskal树+dfs序上的主席树+倍增)

版权声明：本人版权意识薄弱，请随意转载 https://blog.csdn.net/Ike940067893/article/details/88761324

Orz PoPoQQQ

• 学到了维护子树信息的时候用 $dfs$序套主席树节省线段树空间.
• 学到了怎么用指针写可持久化线段树…emmm…

CODE

只贴上3551加强版带强制在线的代码

#include <queue>
#include <cctype>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
typedef long long LL;

char cb[1<<15],*cs=cb,*ct=cb;
#define getc() (cs==ct&&(ct=(cs=cb)+fread(cb,1,1<<15,stdin),cs==ct)?0:*cs++)
template<class T>inline void read(T &res) {
    char ch; int flg = 1; for(;!isdigit(ch=getc());)if(ch=='-')flg=-flg;
    for(res=ch-'0';isdigit(ch=getc());res=res*10+ch-'0'); res*=flg;
}

const int MAXN = 200005;
const int MAXM = 500005;

struct edge{ int u, v, w; }e[MAXM];
inline bool cmp(const edge &A, const edge &B) { return A.w < B.w; }

int n, m, q, tot, w[MAXN], b[MAXN], bel[MAXN], in[MAXN], out[MAXN], id[MAXN], tmr;

int fir[MAXN], to[MAXN], nxt[MAXN], f[MAXN][18], g[MAXN][18], cnt;

struct seg {
	
	seg *ls, *rs;
	int sum;
	
	inline void* operator new (size_t, seg *l, seg *r, int _) {
		seg *re;
		static seg *mempool, *C;
		if(C == mempool) mempool = (C = new seg[1<<15]) + (1<<15);
		re = C++;
		re->ls = l;
		re->rs = r;
		re->sum = _;
		return re;
	}

}*rt[MAXN];

inline void Add(int u, int v) {
	to[++cnt] = v; nxt[cnt] = fir[u]; fir[u] = cnt;
}

int find(int x) {
	if(bel[x] == x || !bel[x]) return bel[x] = x;
	else return bel[x] = find(bel[x]);
}
inline void Kruskal() {
	sort(e + 1, e + m + 1, cmp);
	for(int i = 1; i <= m; ++i) {
		int x = find(e[i].u), y = find(e[i].v);
		if(x != y) { ++n;
			Add(n, x), Add(n, y);
			f[x][0] = f[y][0] = n;
			g[x][0] = g[y][0] = e[i].w;
			bel[x] = bel[y] = n;
		}
	}
}

void dfs(int x) {
	id[in[x] = ++tmr] = x;
	for(int i = fir[x]; i; i = nxt[i])
		dfs(to[i]);
	out[x] = tmr;
}

inline int Get_rt(int x, int lim) {
	for(int j = 17; ~j; --j)
		if(f[x][j] && g[x][j] <= lim)
			x = f[x][j];
	return x;
}

seg* insert(seg *p, int l, int r, int x) {
	if(l == r) return new(0x0, 0x0, p->sum+1) seg;
	int mid = (l + r) >> 1;
	if(x <= mid) return new(insert(p->ls, l, mid, x), p->rs, p->sum+1) seg;
	else return new(p->ls, insert(p->rs, mid+1, r, x), p->sum+1) seg;
}

int query(seg *x, seg *y, int l, int r, int k) {
	if(l == r) return l;
	int mid = (l + r) >> 1;
	if(y->rs->sum - x->rs->sum >= k) return query(x->rs, y->rs, mid+1, r, k);
	else return query(x->ls, y->ls, l, mid, k - y->rs->sum + x->rs->sum);
};

int main () {
	read(n), read(m), read(q);
	for(int i = 1; i <= n; ++i)
		read(w[i]), b[++tot] = w[i];

	sort(b + 1, b + tot + 1);
	tot = unique(b + 1, b + tot + 1) - b - 1;

	for(int i = 1; i <= n; ++i)
		w[i] = lower_bound(b + 1, b + tot + 1, w[i]) - b;

	for(int i = 1; i <= m; ++i)
		read(e[i].u), read(e[i].v), read(e[i].w);

	Kruskal();
	
	dfs(n);
	
	for(int j = 1; j < 18; ++j)
		for(int i = 1; i <= n; ++i) if(f[i][j-1])
			f[i][j] = f[f[i][j-1]][j-1],
			g[i][j] = max(g[i][j-1], g[f[i][j-1]][j-1]);
	
	rt[0] = new(0x0, 0x0, 0) seg; //init
	rt[0]->ls = rt[0]->rs = rt[0];
	
	for(int i = 1; i <= n; ++i)
		if(w[id[i]]) rt[i] = insert(rt[i-1], 0, tot, w[id[i]]);
		else rt[i] = rt[i-1];
	
	int ans = 0, v, x, k; b[0] = -1;
	while(q--) {
		read(v), read(x), read(k);
		v ^= ans, x ^= ans, k ^= ans;
		int root = Get_rt(v, x);
		if(out[root]-in[root]+1 < k) printf("%d\n", ans = -1);
		else printf("%d\n", ans = b[query(rt[in[root]-1], rt[out[root]], 0, tot, k)]);
		if(!~ans) ans = 0;
	}
}