Submission #55065

#	Time	Username	Problem	Language	Result	Execution time	Memory
55065		ksun48	Railway Trip (JOI17_railway_trip)	C++14	25 / 100	2067 ms	26476 KiB

railway_trip

#include <bits/stdc++.h>
using namespace std;
typedef long long LL;

int main(){
	cin.sync_with_stdio(0); cin.tie(0);
	int next[2][100000][20]; // next stop of level <= j, you are <= j+1 (taking trains of j+1)
	int idx[100000][21];
	//int next[2][1000][20]; // next stop of level <= j, you are <= j+1 (taking trains of j+1)
	//int idx[1000][21];
	int n, k, q;
	cin >> n >> k >> q;
	vector<int> level(n);
	for(int i = 0; i < n; i++){
		cin >> level[i];
		level[i] = k - level[i];
	}
	vector<pair<int,int> > queries;
	for(int i = 0; i < q; i++){
		int a, b;
		cin >> a >> b;
		a--; b--;
		queries.push_back({a,b});
	}
	for(int j = 0; j <= k; j++){
		int cur = 0;
		for(int i = 0; i < n; i++){
			if(level[i] <= j){
				idx[i][j] = cur;
				cur++;
			}
		}
	}
	for(int j = 0; j < k; j++){
		int prev = 0;
		for(int i = 0; i < n; i++){
			if(level[i] > j+1) continue;
			if(level[i] <= j){
				prev = i;
			}
			next[0][i][j] = prev;
		}
		prev = n-1;
		for(int i = n-1; i >= 0; i--){
			if(level[i] > j+1) continue;
			if(level[i] <= j){
				prev = i;
			}
			next[1][i][j] = prev;
		}
	}
	for(int zz = 0; zz < queries.size(); zz++){
		pair<int,int> stuff[2][2]; // person, then side
		stuff[0][0] = stuff[0][1] = {queries[zz].first, 0};
		stuff[1][0] = stuff[1][1] = {queries[zz].second, 0};
		int ans = 1000000000;
		for(int j = k-1; j >= 0; j--){
			// go to level j
			for(int p = 0; p < 2; p++){
				pair<int,int> newstuff[2];
				newstuff[0] = make_pair(next[0][stuff[p][0].first ][j], 1000000000);
				newstuff[1] = make_pair(next[1][stuff[p][1].first ][j], 1000000000);
				for(int i = 0; i < 2; i++){
					pair<int,int> x = stuff[p][i];
					// go left from x, go right from x;
					int loc = x.first;
					int dist = x.second;
					for(int dir = 0; dir < 2; dir++){
						int newloc = next[dir][loc][j];
						int newdist = dist + abs(idx[ loc ][j+1] - idx[ newloc ][j+1]);
						for(int qq = 0; qq < 2; qq++){
							if(newstuff[qq].first == newloc){
								newstuff[qq].second = min(newstuff[qq].second, newdist);
							}
						}
					}
				}
				stuff[p][0] = newstuff[0];
				stuff[p][1] = newstuff[1];
			}
			// find ans
			for(int i0 = 0; i0 < 2; i0++){
				pair<int,int> x0 = stuff[0][i0];
				for(int i1 = 0; i1 < 2; i1++){
					pair<int,int> x1 = stuff[1][i1];
					ans = min(ans, x0.second + x1.second + abs(idx[x0.first][j] - idx[x1.first][j]));
				}
			}
		}
		cout << ans - 1 << '\n';
	}
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 15
• Subtask 3: 25 / 25
• Subtask 4: 0 / 55