BZOJ4896 [Thu Summer Camp2016]补退选 【trie树】

题目链接

BZOJ4896

题解

\(thu\)怎么那么喜欢出\(trie\)树的题。。。

我们当然可以按题意模拟建\(trie\)

询问的时候，由于存在删除操作，不满足单调性，不能直接二分答案

我们就在每个节点上用\(vector\)储存每个值第一次出现的时间点

每次询问找到那个点二分一下即可

#include<algorithm>
#include<iostream>
#include<cstring>
#include<cstdio>
#include<vector>
#include<cmath>
#include<map>
#define Redge(u) for (int k = h[u],to; k; k = ed[k].nxt)
#define REP(i,n) for (int i = 1; i <= (n); i++)
#define mp(a,b) make_pair<int,int>(a,b)
#define cls(s) memset(s,0,sizeof(s))
#define cp pair<int,int>
#define LL long long int
#define pb(x) push_back(x)
using namespace std;
const int maxn = 100005,maxm = 7000005,INF = 1000000000;
inline LL read(){
	LL out = 0,flag = 1; char c = getchar();
	while (c < 48 || c > 57){if (c == '-') flag = -1; c = getchar();}
	while (c >= 48 && c <= 57){out = (out << 3) + (out << 1) + c - 48; c = getchar();}
	return out * flag;
}
int n,lans;
int ch[maxm][10],sum[maxm],mx[maxm],cnt;
vector<cp> t[maxm];
char s[70];
void ins(int now,int v){
	int u = 0,id,len = strlen(s + 1);
	for (int i = 1; i <= len; i++){
		id = s[i] - 'a';
		sum[u] += v;
		if (sum[u] > mx[u]) t[u].pb(mp(sum[u],now)),mx[u] = sum[u];
		u = ch[u][id] ? ch[u][id] : ch[u][id] = ++cnt;
	}
	sum[u] += v;
	if (sum[u] > mx[u]) t[u].pb(mp(sum[u],now)),mx[u] = sum[u];
}
int query(LL v){
	int u = 0,len = strlen(s + 1);
	for (int i = 1; i <= len; i++)
		u = ch[u][s[i] - 'a'];
	int l = 0,r = t[u].size() - 1,mid;
	while (l < r){
		mid = l + r >> 1;
		if (t[u][mid].first > v) r = mid;
		else l = mid + 1;
	}
	return t[u][l].first > v ? t[u][l].second : -1;
}
int main(){
	n = read(); int opt; LL a,b,c,v;
	for (int i = 1; i <= n; i++){
		opt = read();
		scanf("%s",s + 1);
		if (opt == 1) ins(i,1);
		else if (opt == 2) ins(i,-1);
		else {
			a = read(); b = read(); c = read();
			v = (1ll * a * abs(lans) % c + b % c) % c;
			if (v >= i) lans = -1;
			else lans = query(v);
			printf("%d\n",lans);
		}
	}
	return 0;
}