Submission #411811

#	Time	Username	Problem	Language	Result	Execution time	Memory
411811		errorgorn	Railway Trip (JOI17_railway_trip)	C++17	20 / 100	2080 ms	8712 KiB

railway_trip

//雪花飄飄北風嘯嘯
//天地一片蒼茫

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
#define ll long long
#define ii pair<ll,ll>
#define iii pair<ii,ll>
#define fi first
#define se second
#define endl '\n'
#define debug(x) cout << #x << " is " << x << endl

#define pub push_back
#define pob pop_back
#define puf push_front
#define pof pop_front
#define lb lower_bound
#define ub upper_bound

#define rep(x,start,end) for(auto x=(start)-((start)>(end));x!=(end)-((start)>(end));((start)<(end)?x++:x--))
#define all(x) (x).begin(),(x).end()
#define sz(x) (int)(x).size()

#define indexed_set tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>
//change less to less_equal for non distinct pbds, but erase will bug

mt19937 rng(chrono::system_clock::now().time_since_epoch().count());

int n,k,q;
int arr[100005];
vector<int> al[100005];

int w[100005];

int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin.exceptions(ios::badbit | ios::failbit);
	
	cin>>n>>k>>q;
	rep(x,1,n+1) cin>>arr[x];
	
	vector<int> stk;
	
	rep(x,1,n+1){
		while (!stk.empty() && arr[stk.back()]<arr[x]){
			al[x].pub(stk.back());
			stk.pob();
		}
		if (!stk.empty()) al[x].pub(stk.back());
		if (!stk.empty() && arr[stk.back()]==arr[x]) stk.pob();
		stk.pub(x);
	}
	
	stk={};
	
	rep(x,n+1,1){
		while (!stk.empty() && arr[stk.back()]<arr[x]){
			al[x].pub(stk.back());
			stk.pob();
		}
		if (!stk.empty()) al[x].pub(stk.back());
		if (!stk.empty() && arr[stk.back()]==arr[x]) stk.pob();
		stk.pub(x);
	}
	
	// rep(x,1,n+1){
		// cout<<x<<": ";
		// for (auto &it:al[x]) cout<<it<<" "; cout<<endl;
	// }
	
	int a,b;
	while (q--){
		cin>>a>>b;
		
		memset(w,63,sizeof(w));
		w[a]=0;
		
		queue<int> qu;
		qu.push(a);
		
		while (!qu.empty()){
			int node=qu.front();
			qu.pop();
			
			for (auto &it:al[node]){
				if (w[it]<1e9) continue;
				w[it]=w[node]+1;
				qu.push(it);
			}
		}
		
		cout<<w[b]-1<<endl;
	}
}

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