Submission #588855

#	Time	Username	Problem	Language	Result	Execution time	Memory
588855		Arnch	Event Hopping (BOI22_events)	C++17	20 / 100	403 ms	59100 KiB

events

// oooo
/*
 har chi delet mikhad bebar ~
 gitar o ba khodet nabar! ~
 ;Amoo_Hasan;
*/

#include<bits/stdc++.h>
//#pragma GCC optimize("O3,no-stack-protector,unroll-loops")
//#pragma GCC target("avx2,fma")

using namespace std;

typedef long long ll;
typedef long double ld;

#define Sz(x) int((x).size())
#define All(x) (x).begin(), (x).end()
#define wtf(x) cout<<#x <<" : " <<x <<endl
//#define endl '\n'

constexpr ll inf = 1e18, N = 1e6 + 10, Log = 30;

int n, q, s[N], e[N];
int val[N], par[N][Log], rpar[N][Log];

void Compress() {
	vector<int> com;
	for(int i = 0; i < n; i++) {
		com.push_back(s[i]), com.push_back(e[i]);
	}
	sort(All(com)), com.erase(unique(All(com)), com.end());
	for(int i = 0; i < n; i++) {
		s[i] = lower_bound(All(com), s[i]) - com.begin();
		e[i] = lower_bound(All(com), e[i]) - com.begin();
	}
}

struct node {
	int cnt;
	node() {
		cnt = -1;
	}
};
struct Seg {
	node x[N << 2];
	int type;
	Seg(int dio) {
		type = dio;
	}
	void build(int l, int r, int v) {
		x[v].cnt = -1;
		if(r - l < 2) return;
		int mid = (l + r) >> 1;
		build(l, mid, 2 * v), build(mid, r, 2 * v + 1);
	}
	node merge(node a, node b) {
		node res = a;
		if(type == 0) {
			if(b.cnt != -1 && (res.cnt == -1 || e[b.cnt] > e[res.cnt])) res = b;
			return res;
		} else {
			if(b.cnt != -1 && (res.cnt == -1 || e[b.cnt] < e[res.cnt])) res = b;
			return res;
		}
	}
	void change(int l, int r, int ind, int val, int v) {
		if(r - l < 2) {
			if(type == 0) {
				if(x[v].cnt == -1 || e[x[v].cnt] < e[val]) 
					x[v].cnt = val;
			} else {
				if(x[v].cnt == -1 || e[x[v].cnt] > e[val]) 
					x[v].cnt = val;
			}
			return;
		}
		int mid = (l + r) >> 1;
		if(ind < mid) change(l, mid, ind, val, 2 * v);
		else change(mid, r, ind, val, 2 * v + 1);
		x[v] = merge(x[2 * v], x[2 * v + 1]);
	}
	node get(int l, int r, int s, int e, int v) {
		node res;
		if(r <= s || l >= e) return res;
		if(l >= s && r <= e) return x[v];
		int mid = (l + r) >> 1;
		return merge(get(l, mid, s, e, 2 * v), get(mid, r, s, e, 2 * v + 1));
	}
} S(0), E(1);

void Pre1() {
	for(int i = 0; i < n; i++) {
		S.change(0, 2 * n, s[i], i, 1);
	}
	for(int i = 0; i < n; i++) {
		int pos = S.get(0, 2 * n, s[i], e[i] + 1, 1).cnt;
		if(pos != -1 && e[pos] > e[i]) par[i][0] = pos;
		else par[i][0] = -1;
	}
	
	for(int lg = 1; lg < Log; lg++) {
		for(int i = 0; i < n; i++) {
			if(par[i][lg - 1] == -1 || par[par[i][lg - 1]][lg - 1] == -1) {
				par[i][lg] = -1; continue;
			}
			par[i][lg] = par[par[i][lg - 1]][lg - 1];
		}
	}
}
void Pre2() {
	E.build(0, 2 * n, 1);
	for(int i = 0; i < n; i++) {
		E.change(0, 2 * n, e[i], i, 1);
	}
	for(int i = 0; i < n; i++) {
		int pos = E.get(0, 2 * n, s[i], e[i] + 1, 1).cnt;
		if(pos != -1 && s[pos] < s[i]) rpar[i][0] = pos;
		else rpar[i][0] = -1;
	}

	for(int lg = 1; lg < Log; lg++) {
		for(int i = 0; i < n; i++) {
			if(rpar[i][lg - 1] == -1 || rpar[rpar[i][lg - 1]][lg - 1] == -1) {
				rpar[i][lg] = -1; continue;
			}
			rpar[i][lg] = rpar[rpar[i][lg - 1]][lg - 1];
		}
	}
}

int main() {
    ios :: sync_with_stdio(0), cin.tie(0);

	cin >>n >>q;
	for(int i = 0; i < n; i++) {
		cin >>s[i] >>e[i];
	}
	Compress();

	Pre1();
	Pre2();

	for(int i = 0; i < q; i++) {
		int x, y; cin >>x >>y;
		x--, y--;

		if(x != y && e[x] > e[y]) {
			cout<<"impossible" <<endl;
			continue;
		}
		if(x == y) {
			cout<<0 <<endl;
			continue;
		}
		if(e[x] >= s[y] && e[x] <= e[y]) {
			cout<<1 <<endl;
			continue;
		}
		
		int t = 0;
		for(int lg = Log - 1; lg >= 0; lg--) {
			if(par[x][lg] == -1) continue;
			if(e[par[x][lg]] < s[y]) {
				x = par[x][lg];
				t += (1 << lg);
			}
		}
		if(par[x][0] != -1 && e[par[x][0]] <= e[y]) {
			cout<<t + 2 <<endl;
			continue;
		}
		for(int lg = Log - 1; lg >= 0; lg--) {
			if(rpar[y][lg] == -1) continue;
			if(s[rpar[y][lg]] > e[x]) {
				y = rpar[y][lg];
				t += (1 << lg);
			}
		}
		if(rpar[y][0] != -1 && s[rpar[y][0]] <= e[x]) {
			cout<<t + 2 <<endl;
			continue;
		}
		cout<<"impossible" <<endl;
	}

    return 0;
}

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