Submission #342575

#	Time	Username	Problem	Language	Result	Execution time	Memory
342575		MarcoMeijer	Highway Tolls (IOI18_highway)	C++14	0 / 100	314 ms	12764 KiB

highway

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

// macros
typedef long long ll;
typedef long double ld;
typedef pair<int, int> ii;
typedef pair<ll, ll> lll;
typedef tuple<int, int, int> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<iii> viii;
typedef vector<ll> vll;
typedef vector<lll> vlll;
#define REP(a,b,c) for(int a=int(b); a<int(c); a++)
#define RE(a,c) REP(a,0,c)
#define RE1(a,c) REP(a,1,c+1)
#define REI(a,b,c) REP(a,b,c+1)
#define REV(a,b,c) for(int a=int(c-1); a>=int(b); a--)
#define FOR(a,b) for(auto& a : b)
#define all(a) a.begin(), a.end()
#define pb push_back
#define popb pop_back
#define fi first
#define se second

const int MX = 2e5;

int n, m;
vi U, V, W;
vi adj[MX];
ll normal;
vi seq;
bitset<MX> visited;
int dst[MX];
int minLB, maxUB;

void fillAdj() {
    RE(i,U.size()) {
        adj[U[i]].push_back(i);
        adj[V[i]].push_back(i);
    }
}
void bfsSequence(vi init, int dist=-1) {
    minLB = -1, maxUB = -1;
    queue<int> q;
    visited.reset();
    FOR(u,init) q.push(u), visited[u]=1, dst[u]=0;
    while(!q.empty()) {
        int u=q.front(); q.pop();
        FOR(e,adj[u]) {
            if(visited[U[e]] && visited[V[e]]) continue;
            if(V[e] == u) swap(U[e], V[e]);
            int v=V[e];
            seq.push_back(e);
            q.push(v); visited[v] = 1;
            dst[v] = dst[u]+1;
            if(dst[v] == dist && minLB == -1) minLB = seq.size();
            if(dst[v] == dist) maxUB = seq.size();
        }
    }
    if(dist == -1) minLB=0, maxUB=m-1;
}
int binarySearchSeq() {
    int lb=minLB, ub=maxUB;
    while(lb != ub) {
        int mid=(lb+ub)/2;
        W.assign(m,1);
        REP(i,0,mid+1) W[seq[i]] = 0;
 
        if(ask(W) == normal) ub=mid;
        else                 lb=mid+1;
    }
    return V[seq[lb]];
}
int getEdgeOnPath() {
    int lb=0, ub=m-1;
    while(lb != ub) {
        int mid=(lb+ub)/2;
        W.assign(m,0);
        RE(i,mid+1) W[i] = 1;
        if(ask(W) == normal) lb=mid+1;
        else ub=mid;
    }
    return lb;
}

void find_pair(int N, vi _U, vi _V, int A, int B) {
    n=N; U=_U; V=_V; m=U.size();

    fillAdj();
    W.assign(m,0);
    normal = ask(W);

    int onPath = getEdgeOnPath();
    int v1 = U[onPath], v2 = V[onPath];
    seq.clear(); seq.push_back(onPath);
    bfsSequence({v1, v2});
    int s = binarySearchSeq();
    seq.clear(); bfsSequence({s}, normal/ll(A));
    int t = binarySearchSeq();
    answer(s,t);
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 7
• Subtask 3: 0 / 6
• Subtask 4: 0 / 33
• Subtask 5: 0 / 18
• Subtask 6: 0 / 31