Submission #1079656

#	Time	Username	Problem	Language	Result	Execution time	Memory
1079656		c2zi6	Longest Trip (IOI23_longesttrip)	C++17	100 / 100	19 ms	700 KiB

longesttrip

#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
#define ff first
#define ss second
#define pb push_back
#define all(a) (a).begin(), (a).end()
#define replr(i, a, b) for (int i = int(a); i <= int(b); ++i)
#define reprl(i, a, b) for (int i = int(a); i >= int(b); --i)
#define rep(i, n) for (int i = 0; i < int(n); ++i)
#define mkp(a, b) make_pair(a, b)
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> PII;
typedef vector<int> VI;
typedef vector<PII> VPI;
typedef vector<VI> VVI;
typedef vector<VVI> VVVI;
typedef vector<VPI> VVPI;
typedef pair<ll, ll> PLL;
typedef vector<ll> VL;
typedef vector<PLL> VPL;
typedef vector<VL> VVL;
typedef vector<VVL> VVVL;
typedef vector<VPL> VVPL;
template<class T> T setmax(T& a, T b) {if (a < b) return a = b; return a;}
template<class T> T setmin(T& a, T b) {if (a < b) return a; return a = b;}
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template<class T>
using indset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#include "longesttrip.h"

int n;

VI rev(VI a) {
    reverse(all(a));
    return a;
}

// int are_connected(VI a, VI b);

VI longest_trip(int N, int D) {
    n = N;
    VI path1;
    VI path2;

    VI order;
    rep(i, n) order.pb(i);
    mt19937 rng(chrono::steady_clock().now().time_since_epoch().count());
    shuffle(all(order), rng);

    path1.pb(order[0]);
    path2.pb(order[1]);
    bool ardyoq = false;
    // ardyoq es gitem or P-n u Q-n kpac chen?
    replr(i, 2, n-1) {
        int R = order[i];
        int P = path1.back();
        int Q = path2.back();
        if (ardyoq) {
            if (are_connected({P}, {R})) {
                path1.pb(R);
                ardyoq = false;
            } else path2.pb(R);
        } else {
            if (are_connected({P}, {R})) path1.pb(R);
            else if (are_connected({Q}, {R})) {
                path2.pb(R);
                ardyoq = true;
            } else {
                for (int x : rev(path2)) path1.pb(x);
                path2 = VI{R};
            }
        }
    }

    if (are_connected({path2[0]}, {path1[0]})) {
        VI ans;
        for (int x : rev(path2)) ans.pb(x);
        for (int x : path1) ans.pb(x);
        return ans;
    }
    if (are_connected({path2.back()}, {path1[0]})) {
        VI ans;
        for (int x : path2) ans.pb(x);
        for (int x : path1) ans.pb(x);
        return ans;
    }
    if (are_connected({path1.back()}, {path2[0]})) {
        VI ans;
        for (int x : path1) ans.pb(x);
        for (int x : path2) ans.pb(x);
        return ans;
    }

    auto getind2 = [&](int ind1){
        auto ardyoq = [&](int x) {
            VI tmp;
            rep(i, x+1) tmp.pb(path2[i]);
            return are_connected({path1[ind1]}, tmp);
        };
        int l = -1, r = path2.size()-1;
        while (l + 1 < r) {
            int m = (l + r) / 2;
            if (ardyoq(m)) r = m;
            else l = m;
        }
        return r;
    };
    auto getind1 = [&]() {
        auto ardyoq = [&](int x) {
            VI a, b;
            rep(i, x+1) a.pb(path1[i]);
            rep(i, path2.size()) b.pb(path2[i]);
            return are_connected(a, b);
        };
        int l = -1, r = path1.size();
        while (l + 1 < r) {
            int m = (l + r) / 2;
            if (ardyoq(m)) r = m;
            else l = m;
        }
        if (r == path1.size()) return -1;
        return r;
    };

    int ind1 = getind1();
    if (ind1 == -1) {
        if (path1.size() > path2.size()) return path1;
        return path2;
    }
    int ind2 = getind2(ind1);

    VI ans;
    replr(i, ind2+1, ind2+1 + path2.size()-1) {
        ans.pb(path2[i%(int)path2.size()]);
    }
    replr(i, ind1, ind1 + path1.size()-1) {
        ans.pb(path1[i%(int)path1.size()]);
    }
    return ans;
}

Compilation message (stderr)

longesttrip.cpp: In lambda function:
longesttrip.cpp:124:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  124 |         if (r == path1.size()) return -1;
      |             ~~^~~~~~~~~~~~~~~

• Subtask 0: 0 / 0
• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 25 / 25
• Subtask 4: 60 / 60