Submission #1167155

#	Time	Username	Problem	Language	Result	Execution time	Memory
1167155		shraefkt	Circle Passing (EGOI24_circlepassing)	C++20	100 / 100	51 ms	12360 KiB

Main

#include <bits/stdc++.h>
using namespace std;
#define int long long
const int MAX = 500007;
const int INF = LLONG_MAX;
int N;
int distance(int x, int y) {
	int dist = abs(x-y);
	dist = min(dist, 2*N-dist);
	return dist;
}
int get_opposite(int x) {
	if (x%N == x) return x + N;
	else return x % N;
}
int32_t main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	int M,Q;
	cin >> N >> M >> Q;
	int best_friend[M]; //other best_friend is +N
	int best_friend_bsta[M*2+3];
	for (int i=0;i<M;i++) {
		cin  >> best_friend[i];
		best_friend_bsta[i+1] = best_friend[i];
		best_friend_bsta[i+M+1] = best_friend[i]+N;
	}
	best_friend_bsta[0] = -1;
	best_friend_bsta[2*M+1] = INF;
	
	int bridge_is_totally_useless_radius = (N+1)/2;
	int bridge_is_useless_radius = N/2-1;
	int x, y;
	for (int i=0;i<Q;i++) {
		cin >> x >> y;
		if (distance(x,y)<=bridge_is_totally_useless_radius) {
			cout << distance(x,y) << endl;
		} else {
			int shortest_path = distance(x,y);
			// binary search for closest neighbours
			
			int lo = 0; int hi = 2*M+1; int mid;
			int left;
			while (lo <= hi) {
				mid = lo + (hi-lo) /2;
				if (best_friend_bsta[mid] > x) 
				{hi = mid-1; left = hi;}
				else {
					lo = mid+1;
					left = mid;
				} 
			}
			lo = 0; hi = 2*M+1;
			int right;
			while (lo <= hi) {
				mid = lo + (hi-lo) /2;
				if (best_friend_bsta[mid] < x) 
				{lo = mid+1;
				right = lo;
			}
				else {
					hi = mid-1;
					right = mid;
				} 
			}
			int left_bestie, right_bestie;
			left_bestie = best_friend_bsta[left];
			right_bestie = best_friend_bsta[right];
			if (left == 0) left_bestie = best_friend_bsta[2*M];
			if (right == 2*M+1) right_bestie = best_friend_bsta[1];
			shortest_path = min(shortest_path,distance(left_bestie,x) + distance(get_opposite(left_bestie),y) + 1);
			shortest_path = min(shortest_path,distance(right_bestie,x) + distance(get_opposite(right_bestie),y) + 1);
			cout << shortest_path << endl;
		}
		
		
	}
	
	
	
	
}

• Subtask 1: 14 / 14
• Subtask 2: 20 / 20
• Subtask 3: 22 / 22
• Subtask 4: 17 / 17
• Subtask 5: 27 / 27