【BZOJ3196】【Luogu P3380】 【模板】二逼平衡树（树套树）

做数据结构一定要平\((fo)\)心\((de)\)静\((yi)\)气\((pi)\)。。。不然会四处出锅的\(QAQ\)

写法：线段树套平衡树，\(O(Nlog^3N)\)。五个操作如果是对于整个区间的，那么就是平衡树板子题。现在既然是放在子区间上的，那么套一个线段树就好啦~

#include <bits/stdc++.h>
using namespace std;

const int N = 50000 + 5;
const int INF = 1e8 + 5;

#define ls (p << 1)
#define rs (p << 1 | 1)
#define mid ((l + r) >> 1)


int n, m, tot, arr[N];

struct FHQ_Node {
	int w, lc, rc, sz, rd;
}t[N << 8];

struct FHQ_Treap {
	
	int rt;
	
	int NewNode (int w) {
		t[++tot] = FHQ_Node {w, 0, 0, 1, rand ()};
		return tot;
	}
	
	void push_up (int p) {
		t[p].sz = 1;
		if (t[p].lc) t[p].sz += t[t[p].lc].sz;
		if (t[p].rc) t[p].sz += t[t[p].rc].sz;
	}
	
	void split (int now, int &A, int &B, int w) {
		if (now == 0) {
			A = B = 0; return;
		}
		if (t[now].w <= w) {
			A = now; split (t[now].rc, t[A].rc, B, w);
		} else {
			B = now; split (t[now].lc, A, t[B].lc, w);
		}
		push_up (now);
	}
	
	int merge (int A, int B) {
		if (A * B == 0) {
			return A + B;
		}
		if (t[A].rd < t[B].rd) {
			t[A].rc = merge (t[A].rc, B); 
			push_up (A); return A;
		} else {
			t[B].lc = merge (A, t[B].lc);
			push_up (B); return B;
		}
	}
	
	int x, y, z;
	
	void Insert (int w) {
		split (rt, x, y, w);
		rt = merge (x, merge (NewNode (w), y));
//		cout << "rt = " << rt << endl;
	}
	
	void Delete (int w) {
		split (rt, x, y, w - 1);
		split (y, y, z, w);
		y = merge (t[y].lc, t[y].rc);
		rt = merge (x, merge (y, z));
	}
	
	int pre (int w) {
		split (rt, x, y, w - 1);
		int p = x;
		if (p == 0) {
			return -0x7fffffff;
		}
		while (t[p].rc != 0) {
			p = t[p].rc;
		}
		rt = merge (x, y);
		return t[p].w;
	}
	
	int nxt (int w) {
		split (rt, x, y, w);
		int p = y;
		if (p == 0) {
			return +0x7fffffff;
		}
		while (t[p].lc != 0) {
			p = t[p].lc;
		}
		rt = merge (x, y);
		return t[p].w;
	}
	
	void print (int p) {
		if (t[p].lc) print (t[p].lc);
//		cout << "p = " << p << " w = " << t[p].w << " sz = " << t[p].sz << endl;
		if (t[p].rc) print (t[p].rc);
	}
	
	int rank (int w) {
		split (rt, x, y, w - 1);
		int ret = t[x].sz + 1;
		rt = merge (x, y); 
//		print (rt); cout << endl;
		return ret;
	}
};

struct Segment_Tree {
	
	FHQ_Treap tree[N << 2];
	
	void modify (int pos, int wpre, int wnew, int l = 1, int r = n, int p = 1) {
//		cout << "p = " << p << endl;
		if (wpre != -1) {tree[p].Delete (wpre);/*cout << "tree[" << p << "].Delete (" << wpre << ");" << endl;*/}
		if (wnew != -1) {tree[p].Insert (wnew);/*cout << "tree[" << p << "].Insert (" << wnew << ");" << endl;*/}
		if (l == r) return;
		if (pos <= mid) {
			modify (pos, wpre, wnew, l, mid + 0, ls);
		} else {
			modify (pos, wpre, wnew, mid + 1, r, rs);
		}
	}
	
	int tot, sta[N];
	
	void get_segment (int nl, int nr, int l = 1, int r = n, int p = 1) {
		if (p == 1) tot = 0;
		if (nl <= l && r <= nr) {
			sta[++tot] = p; return;
		}
		if (nl <= mid) get_segment (nl, nr, l, mid + 0, ls);
		if (mid < nr) get_segment (nl, nr, mid + 1, r, rs);
	} 
	
	int rank (int l, int r, int w) {
		get_segment (l, r);
		int ret = 1;
		for (int i = 1; i <= tot; ++i) {
//			cout << tree[sta[i]].rank (w) << endl;
			ret += (tree[sta[i]].rank (w) - 1);
		}
//		cout << "val = " << w << " rank = " << ret << endl;
		return ret;
	} 
	
	int kth (int l, int r, int k) {
		int lval = 0, rval = INF;
//		cout << "k = " << k << endl;
		while (lval < rval) {
//			getchar ();
			int _mid = (lval + rval + 1) >> 1;
//			cout << "lval = " << lval << " rval = " << rval << " mid = " << _mid << " rank " << k << " = " << rank (l, r, _mid) << endl;
			if (rank (l, r, _mid) <= k) {
				lval = _mid;
			} else {
				rval = _mid - 1;
			}
		}
		return lval;
	}
	
	int pre (int l, int r, int w) {
		get_segment (l, r);
		int maxw = -0x7fffffff;
		for (int i = 1; i <= tot; ++i) {
			maxw = max (maxw, tree[sta[i]].pre (w));
		}
		return maxw;
	}
	
	int nxt (int l, int r, int w) {
		get_segment (l, r);
		int minw = +0x7fffffff;
		for (int i = 1; i <= tot; ++i) {
			minw = min (minw, tree[sta[i]].nxt (w));
		}
		return minw;
	}
}tr;

int read () {
	int s = 0, ch = getchar ();
	while (!isdigit (ch)) {
		ch = getchar ();
	}
	while (isdigit (ch)) {
		s = s * 10 + ch - '0';
		ch = getchar ();
	}
	return s;
}

int main () {
//	freopen ("data.in", "r", stdin);
	srand (time (NULL));
	n = read (), m = read ();
	for (int i = 1; i <= n; ++i) {
		int w = read ();
		tr.modify (i, -1, w);
		arr[i] = w;
//		cout << endl;
	}
	int opt, pos, l, r, k;
	for (int i = 1; i <= m; ++i) {
		opt = read ();
		if (opt == 1) {
			l = read (), r = read (), k = read ();
			cout << tr.rank (l, r, k) << endl;
		}
		if (opt == 2) {
			l = read (), r = read (), k = read ();
			cout << tr.kth (l, r, k) << endl;
		}	
		if (opt == 3) {
			pos = read (), k = read ();
			tr.modify (pos, arr[pos], k);
			arr[pos] = k;
		} 
		if (opt == 4) {
			l = read (), r = read (), k = read ();
			cout << tr.pre (l, r, k) << endl;
		}
		if (opt == 5) {
			l = read (), r = read (), k = read ();
			cout << tr.nxt (l, r, k) << endl;
		}
	}
}