5333. 【NOIP2017提高A组模拟8.23】大新闻

Description

Input

Output

Sample Input

Sample Output

Data Constraint

Hint

题解

代码

#include <bits/stdc++.h>

using namespace std;

typedef long long LL;

const int N = 200010;
const int LG = 33;

#define child int t0, int &t, int l = 1, int r = 1e9
#define mid ((l + r) >> 1)
#define ls a[t0].l, a[t].l, l, mid
#define rs a[t0].r, a[t].r, mid + 1, r

struct NOTE
{
int l,r,s;
}a[N * 2 * LG];

int root[N * 2];
int tim;
int tot;

int f
;
int n, m, x, y, k, op;

void rev(child)
{
a[t = ++tot] = a[t0], ++a[t].s;
if (l == r)
return;
if (x <= mid)
rev(ls);
else rev(rs);
}

int ask(child)
{
if (l == r)
return l;
int tmp = a[a[t0].l].s - a[a[t].l].s;
if (k <= tmp)
return ask(ls);
return k -= tmp, ask(rs);
}

int main()
{
freopen("news.in","r",stdin);
freopen("news.out","w",stdout);

scanf("%d%d",&n,&m);
for (int i = 1; i <= n; i++)
scanf("%d", f + i);
for (int i = n; i >= 1; i--)
{
x = f[i];
++tim;
root[tim] = root[tim - 1];
rev(root[tim - 1], root[tim]);
}
while (m--)
{
scanf("%d", &op);
if (op == 1)
{
--tim;
continue;
}
if (op == 2)
{
scanf("%d", &x);
++tim;
root[tim] = root[tim - 1];
rev(root[tim - 1], root[tim]);
continue;
}
scanf("%d%d%d", &x, &y, &k);
printf("%d\n", ask(root[tim - x + 1], root[tim - y]));
}
}