| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 1259866 | nguyenhuythach | Toll (BOI17_toll) | C++20 | 0 ms | 0 KiB |
#include<iostream>// #include<bits/stdc++.h>
#include<algorithm>
#include<random>
#include<chrono>
#include<cstdlib>
#include<ctime>
#include<numeric>
#include<vector>
#include<stack>
#include<map>
#include<set>
#include<queue>
#include<iomanip>
#define int long long
#define ll long long
#define L LLONG_MAX
#define fi first
#define se second
#define pii pair<int,int>
#define sz(a) ((int)a.size())
#define FOR(i,j,k) for(int i=j;i<=k;i++)
#define REP(i,k,j) for(int i=k;i>=j;i--)
#define FORD(i,a) for(auto i:a)
#define rngdcl mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count())
#define random(l,r) ((l)+(rng()%(r-l+1)))
using namespace std;
const int nmax=5e4+69;
int n,m,k,q;
vector<pii> adj[nmax];
vector<pii> rev[nmax];
int suf[17][nmax][6],pfx[17][nmax][6];
void input()
{
cin >> k >> n >> m >> q;
FOR(i,1,m)
{
int u,v,w; cin >> u >> v >> w;
u++; v++;
adj[u].push_back({v,w});
rev[v].push_back({u,w});
}
}
pii pos(int x)
{
return {(x-1)/k+1,(x-1)%k+1};
}
void dnc(int l,int r,int lv)
{
if(pos(l).fi==pos(r).fi || l>=r) return;
int mid=(l+r)/2;
//precase
int sl=mid,sr=mid;
while(pos(sl).fi==pos(mid).fi && sl>1) sl--;
while(pos(sr).fi==pos(mid).fi && sr<n) sr++;
FOR(i,sl,sr) suf[lv][i][pos(i).se]=0;
FOR(i,sl,sr) pfx[lv][i][pos(i).se]=0;
//build
REP(u,sl,l)
{
FORD(i,adj[u])
{
FOR(j,1,k)
{
if(suf[lv][i.fi][j]!=L) suf[lv][u][j]=min(suf[lv][u][j],suf[lv][i.fi][j]+i.se);
}
}
}
FOR(u,sr,r)
{
FORD(i,rev[u])
{
FOR(j,1,k)
{
if(pfx[lv][i.fi][j]!=L) pfx[lv][u][j]=min(pfx[lv][u][j],pfx[lv][i.fi][j]+i.se);
}
}
}
//recursion
dnc(l,mid-1,lv+1);
dnc(mid+1,r,lv+1);
}
pii find(int l,int r,int lv,int lf,int rt)
{
int mid=(l+r)/2;
if(l<=lf && rt<=r && lf<=mid && mid<=rt) return {lv,mid};
if(l<=lf && rt<=mid) return find(l,mid,lv+1,lf,rt);
else return find(mid+1,r,lv+1,lf,rt);
}
void solve()
{
//preprocess
FOR(i,0,16) FOR(j,1,n) FOR(k,1,5)
{
suf[i][j][k]=L;
pfx[i][j][k]=L;
}
dnc(1,n,1);
// FOR(lv,1,4) {FOR(i,1,n) {FOR(j,1,k) cout << suf[lv][i][j] << ' '; cout << '\n';} cout << '\n';}
//query
while(q--)
{
int l,r; cin >> l >> r;
l++; r++;
pii save=find(1,n,1,l,r);
int mid=save.se;
int lv=save.fi;
int ans=L;
if(pos(l).fi+1==pos(r).fi)
{
FORD(i,adj[l]) if(i.fi==r) ans=i.se;
}
else
{
FOR(i,1,k) if(suf[lv][l][i]!=L && pfx[lv][r][i]!=L) ans=min(ans,suf[lv][l][i]+pfx[lv][r][i]);
}
if(ans==L) cout << -1 << '\n';
else cout << ans << '\n';
}
}
signed main()
{
//freopen(".inp", "r", stdin);
//freopen(".out", "w", stdout);
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
input();
solve();
}