Submission #589015

#	Time	Username	Problem	Language	Result	Execution time	Memory
589015		ParsaEs	Event Hopping (BOI22_events)	C++17	50 / 100	1577 ms	5908 KiB

events

//InTheNameOfGOD
//PRS;)
#pragma GCC optimize("unroll-loops", "Ofast", "O3")
#include<iostream>
#include<algorithm>
#define rep(i, l, r) for(ll i = l; i < r; i++)
#define min(x, y) (x < y ? x : y)
#define max(x, y) (x > y ? x : y)
#define X first
#define Y second
typedef int ll;
using namespace std;
typedef pair<ll, ll> pl;
typedef pair<ll, pl> pi;
constexpr ll inf = 2e9, xn = 1e5 + 5, s = 317;
ll d[xn], p[xn], sx[xn], x[xn], m[s];
pi e[xn];
int main()
{
    ll n, q;
    scanf("%d %d", &n, &q);
    rep(i, 0, n) scanf("%d %d", &e[i].Y.X, &e[i].X), e[i] = {-e[i].X, {-e[i].Y.X, i}};
    sort(e, e + n);
    rep(i, 0, s) m[i] = -inf;
    rep(i, 0, n)
    {
        sx[i] = x[i] = -1;
        rep(j, 0, i / s + 1) if(e[i].X <= m[j])
        {
            rep(k, j * s, min((j + 1) * s, i)) if(e[i].X <= e[k].Y.X)
            {
                if(k / s < i / s) sx[i] = k, d[i] = 1;
                else if(sx[k] >= 0) sx[i] = sx[k], d[i] = d[k] + 1;
                x[i] = k;
                break;
            }
            break;
        }
        m[i / s] = max(e[i].Y.X, m[i / s]), p[e[i].Y.Y] = i;
    }
    while(q--)
    {
        ll l, r, ans = 0;
        scanf("%d %d", &l, &r);
        if(l == r)
        {
            printf("0\n");
            continue;
        }
        l = p[l - 1], r = p[r - 1];
        if(e[l].X < e[r].X)
        {
            printf("impossible\n");
            continue;
        }
        if(e[l].X == e[r].X)
        {
            printf("1\n");
            continue;
        }
        while(sx[l] >= r) ans += d[l], l = sx[l];
        while(x[l] >= r) l = x[l], ans++;
        if(r == l)
        {
            printf("%d\n", ans);
            continue;
        }
        ll z = e[r].Y.X, mx = e[r].Y.X;
        bool f = 1;
        rep(i, r + 1, l + 1)
        {
            if(z < e[i].X && mx < e[i].X)
            {
                f = 0;
                break;
            }
            if(z < e[i].X) z = mx, ans++;
            mx = max(mx, e[i].Y.X);
        }
        if(f) printf("%d\n", ans + 1);
        else printf("impossible\n");
    }
}

Compilation message (stderr)

events.cpp: In function 'int main()':
events.cpp:21:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   21 |     scanf("%d %d", &n, &q);
      |     ~~~~~^~~~~~~~~~~~~~~~~
events.cpp:22:23: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   22 |     rep(i, 0, n) scanf("%d %d", &e[i].Y.X, &e[i].X), e[i] = {-e[i].X, {-e[i].Y.X, i}};
      |                  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
events.cpp:44:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   44 |         scanf("%d %d", &l, &r);
      |         ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 15 / 15
• Subtask 4: 15 / 15
• Subtask 5: 0 / 20
• Subtask 6: 0 / 30