P1198 [JSOI2008]最大数

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分析

• 查询数列倒数$L$个数的最大值
• 添加一个值到数列末尾

区间最值，动态添加，$Splay$不是也能干这些事情吗 这里无非就是为了要维护一个最大值而已，记得预插入两个哨兵（最小值和最大值） 那么请看 $push\_up$ 函数，此题得解

行！ 那就用$Splay$

代码

//P1198
/*
  @Author: YooQ
*/
#include <bits/stdc++.h>
using namespace std;
#define sc scanf
#define pr printf
#define ll long long
#define int long long
#define FILE_OUT freopen("out", "w", stdout);
#define FILE_IN freopen("in", "r", stdin);
#define debug(x) cout << #x << ": " << x << "\n";
#define AC 0
#define WA 1
#define INF 0x3f3f3f3f
const ll MAX_N = 1e6+5;
const ll MOD = 1e9+7;
int N, M, K;

struct Tr {
	int k, fa, v, maxx;
	int son[2];
	int& l = son[0];
	int& r = son[1];
}tr[MAX_N];
int root = 0;
int indx = 0;

void push_up(int rt) {
	tr[rt].maxx = max(max(tr[tr[rt].l].maxx, tr[tr[rt].r].maxx), tr[rt].v);
}

int which(int x) {
	return tr[tr[x].fa].son[1] == x;
}

void rotate(int x) {
	int p = tr[x].fa;
	int q = tr[p].fa;
	int side = which(x);
	
	tr[tr[p].son[side] = tr[x].son[side^1]].fa = p;
	tr[tr[x].son[side^1] = p].fa = x;
	tr[x].fa = q;
	if (q) tr[q].son[tr[q].son[1] == p] = x;
	
	push_up(p);
	push_up(x);
}

void splay(int x, int tar) {
	for (int p; (p = tr[x].fa) != tar; rotate(x)) {
		if (tr[p].fa != tar) rotate(which(x) == which(p) ? p : x);
	}
	if (!tar) root = x;
}

int find(int x) {
	int rt = root;
	while (tr[rt].son[x > tr[rt].k] && x != tr[rt].k) {
		rt = tr[rt].son[x > tr[rt].k];
	}
	splay(rt, 0);
	return rt;
}

void insert(int x, int v) {
	int rt = root, p = 0;
	while (rt) {
		p = rt;
		rt = tr[rt].son[x > tr[rt].k];
	}
	rt = ++indx;
	tr[rt].k = x;
	tr[rt].maxx = tr[rt].v = v;
	tr[rt].fa = p;
	if (p) tr[p].son[x > tr[p].k] = rt;
	
	splay(rt, 0);
}

void print(int rt) {
	if (!rt) return;
	cout << tr[rt].v << "++";
	print(tr[rt].l);
	print(tr[rt].r);
}

int id = 0;
int calc(int x) {
	int pre = find(id - x);
	int nxt = find(N+1);
	splay(pre, 0);splay(nxt, pre);
	return tr[tr[nxt].l].maxx;
}

void solve(){
	cin >> N >> M;
	char opt[5];
	int x;
	
	insert(0, -1e18);
	insert(N+1, -1e18);
	
	int pre = 0;
	for (int i = 1; i <= N; ++i) {
		cin >> opt >> x;
		if (*opt == 'A') {
			insert(++id, (x+pre) % M);
		} else {
			cout << (pre = calc(x))<< "\n";
		}
	}
}

signed main()
{
	#ifndef ONLINE_JUDGE
	//FILE_IN
	FILE_OUT
	#endif
	int T = 1;//cin >> T;
	while (T--) solve();

	return AC;
}