Submission #400301

#	Time	Username	Problem	Language	Result	Execution time	Memory
400301		duality	Railway Trip (JOI17_railway_trip)	C++11	100 / 100	416 ms	49564 KiB

railway_trip

#define DEBUG 0

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

#if DEBUG
// basic debugging macros
int __i__,__j__;
#define printLine(l) for(__i__=0;__i__<l;__i__++){cout<<"-";}cout<<endl
#define printLine2(l,c) for(__i__=0;__i__<l;__i__++){cout<<c;}cout<<endl
#define printVar(n) cout<<#n<<": "<<n<<endl
#define printArr(a,l) cout<<#a<<": ";for(__i__=0;__i__<l;__i__++){cout<<a[__i__]<<" ";}cout<<endl
#define print2dArr(a,r,c) cout<<#a<<":\n";for(__i__=0;__i__<r;__i__++){for(__j__=0;__j__<c;__j__++){cout<<a[__i__][__j__]<<" ";}cout<<endl;}
#define print2dArr2(a,r,c,l) cout<<#a<<":\n";for(__i__=0;__i__<r;__i__++){for(__j__=0;__j__<c;__j__++){cout<<setw(l)<<setfill(' ')<<a[__i__][__j__]<<" ";}cout<<endl;}

// advanced debugging class
// debug 1,2,'A',"test";
class _Debug {
    public:
        template<typename T>
        _Debug& operator,(T val) {
            cout << val << endl;
            return *this;
        }
};
#define debug _Debug(),
#else
#define printLine(l)
#define printLine2(l,c)
#define printVar(n)
#define printArr(a,l)
#define print2dArr(a,r,c)
#define print2dArr2(a,r,c,l)
#define debug
#endif

// define
#define MAX_VAL 999999999
#define MAX_VAL_2 999999999999999999LL
#define EPS 1e-6
#define mp make_pair
#define pb push_back

// typedef
typedef unsigned int UI;
typedef long long int LLI;
typedef unsigned long long int ULLI;
typedef unsigned short int US;
typedef pair<int,int> pii;
typedef pair<LLI,LLI> plli;
typedef vector<int> vi;
typedef vector<LLI> vlli;
typedef vector<pii> vpii;
typedef vector<plli> vplli;

// ---------- END OF TEMPLATE ----------

int L[100000];
struct query { int A,B,i; };
vector<query> vv;
int ans[100000];
pii p[200000];
set<int> adjList[100000];
vi adjList2[200000];
vi S;
int size[200000],visited[200000];
int doDFS(int u,int p) {
    int i;
    size[u] = 1;
    for (i = 0; i < adjList2[u].size(); i++) {
        int v = adjList2[u][i];
        if (!visited[v] && (v != p)) size[u] += doDFS(v,u);
    }
    return size[u];
}
int centroid(int u) {
    int i,p = -1,r = u;
    doDFS(r,-1);
    while (1) {
        int h = -1;
        for (i = 0; i < adjList2[u].size(); i++) {
            int v = adjList2[u][i];
            if (!visited[v] && (v != p)) {
                if ((h == -1) || (size[v] > size[h])) h = v;
            }
        }
        if (((h == -1) || (size[h] <= size[r]/2)) && (size[r]-size[u] <= size[r]/2)) break;
        else p = u,u = h;
    }
    return u;
}
int dist[2][100000];
vi vvv;
queue<int> Q;
int doBFS(int u,int *dist) {
    Q.push(u),dist[u] = 0,vvv.pb(u);
    while (!Q.empty()) {
        int u = Q.front();
        Q.pop();

        for (auto it = adjList[u].begin(); it != adjList[u].end(); it++) {
            int v = *it;
            if (dist[v] == -1) {
                dist[v] = dist[u]+1,vvv.pb(v);
                Q.push(v);
            }
        }
    }
    return 0;
}
int f(int d) {
    return (d == -1) ? 1e9:d;
}
int top[200000];
int decompose(int u,vector<query> vv) {
    int i;
    u = centroid(u);
    if (!vv.empty()) {
        doBFS(p[u].first,dist[0]);
        doBFS(p[u].second,dist[1]);
    }
    vector<query> in,out;
    vector<query> L,R;
    for (i = 0; i < vv.size(); i++) {
        ans[vv[i].i] = min(ans[vv[i].i],f(dist[0][vv[i].A])+f(dist[0][vv[i].B]));
        ans[vv[i].i] = min(ans[vv[i].i],f(dist[1][vv[i].A])+f(dist[1][vv[i].B]));
    }
    for (auto it = adjList[p[u].first].begin(); it != adjList[p[u].first].end(); it++) adjList[*it].erase(p[u].first);
    for (auto it = adjList[p[u].second].begin(); it != adjList[p[u].second].end(); it++) adjList[*it].erase(p[u].second);
    adjList[p[u].first].clear(),adjList[p[u].second].clear();
    for (i = 0; i < vvv.size(); i++) dist[0][vvv[i]] = dist[1][vvv[i]] = -1;
    for (i = 0; i < vv.size(); i++) {
        if ((vv[i].A == p[u].first) || (vv[i].B == p[u].first)) continue;
        if ((vv[i].A == p[u].second) || (vv[i].B == p[u].second)) continue;
        int a = (vv[i].A > p[u].first) && (vv[i].A < p[u].second);
        int b = (vv[i].B > p[u].first) && (vv[i].B < p[u].second);
        if (a == b) {
            if (a) in.pb(vv[i]);
            else {
                if (!top[u]) out.pb(vv[i]);
                else {
                    if ((min(vv[i].A,vv[i].B) < p[u].first) && (max(vv[i].A,vv[i].B) > p[u].second)) continue;
                    else {
                        if (max(vv[i].A,vv[i].B) < p[u].first) L.pb(vv[i]);
                        else R.pb(vv[i]);
                    }
                }
            }
        }
    }
    vvv.clear();
    visited[u] = 1;
    for (i = 0; i < adjList2[u].size(); i++) {
        int v = adjList2[u][i];
        if (!visited[v]) {
            if ((p[v].first >= p[u].first) && (p[v].second <= p[u].second)) decompose(v,in);
            else {
                if (!top[u]) decompose(v,out);
                else {
                    if (p[v].first < p[u].first) decompose(v,L);
                    else decompose(v,R);
                }
            }
        }
    }
    return 0;
}
int main() {
    int i;
    int N,K,Q,A,B;
    scanf("%d %d %d",&N,&K,&Q);
    for (i = 0; i < N; i++) scanf("%d",&L[i]);
    for (i = 0; i < Q; i++) {
        scanf("%d %d",&A,&B);
        vv.pb((query){A-1,B-1,i}),ans[i] = 1e9;
    }

    int c = 0;
    for (i = 0; i < N; i++) {
        if (i > 0) {
            p[c++] = mp(i-1,i);
            S.pb(c-1);
            adjList[i-1].insert(i);
            adjList[i].insert(i-1);
        }
        int e = 1;
        while ((S.size() >= 2) && (L[p[S[S.size()-2]].second] < L[i])) {
            if (e && (L[p[S[S.size()-2]].first] > L[p[S[S.size()-2]].second])) {
                adjList[p[S[S.size()-2]].first].insert(i);
                adjList[i].insert(p[S[S.size()-2]].first);
            }
            e &= L[p[S[S.size()-2]].first] < L[i];
            p[c++] = mp(p[S[S.size()-2]].first,i);
            adjList2[c-1].pb(S[S.size()-2]);
            adjList2[S[S.size()-2]].pb(c-1);
            adjList2[c-1].pb(S.back());
            adjList2[S.back()].pb(c-1);
            S.pop_back(),S.pop_back(),S.pb(c-1);
        }
    }
    for (i = 0; i < S.size(); i++) top[S[i]] = 1;
    for (i = 1; i < S.size(); i++) {
        adjList2[S[i-1]].pb(S[i]);
        adjList2[S[i]].pb(S[i-1]);
    }
    memset(dist,-1,sizeof(dist));
    decompose(S[0],vv);
    for (i = 0; i < Q; i++) printf("%d\n",ans[i]-1);

    return 0;
}

Compilation message (stderr)

railway_trip.cpp: In function 'int main()':
railway_trip.cpp:171:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  171 |     scanf("%d %d %d",&N,&K,&Q);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~
railway_trip.cpp:172:34: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  172 |     for (i = 0; i < N; i++) scanf("%d",&L[i]);
      |                             ~~~~~^~~~~~~~~~~~
railway_trip.cpp:174:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  174 |         scanf("%d %d",&A,&B);
      |         ~~~~~^~~~~~~~~~~~~~~

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