제출 #848632

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
848632		piOOE	가장 긴 여행 (IOI23_longesttrip)	C++17	100 / 100	22 ms	1108 KiB

longesttrip

#include "longesttrip.h"
#include <bits/stdc++.h>

using namespace std;

std::vector<int> longest_trip(int N, int D) {
    mt19937 rnd(228);

    vector<int> a, b, ord(N);
    iota(ord.begin(), ord.end(), 0);
    shuffle(ord.begin(), ord.end(), rnd);
    int known = -1;

    for (int x : ord) {
        if (a.empty() || b.empty()) {
            (a.empty() ? a : b).push_back(x);
            continue;
        }
        if (rnd() % 2) {
            swap(a, b);
        }
        if (1) {
            int res = are_connected({a.back()}, {x});
            if (res == 1) {
                a.push_back(x);
                known = -1;
            } else if (known != -1) {
                if (known == 1) { // unreachable
                    a.insert(a.end(), b.rbegin(), b.rend());
                    b = {x};
                    known = -1;
                } else {
                    b.push_back(x);
                    known = 0;
                }
            } else {
                res = are_connected({b.back()}, {x});
                if (res == 0) {
                    a.insert(a.end(), b.rbegin(), b.rend());
                    b = {x};
                    known = -1;
                } else {
                    b.push_back(x);
                    known = 0;
                }
            }
        } else {
            if (are_connected({a.back()}, {x})) {
                a.push_back(x);
            } else if (are_connected({b.back()}, {x})) {
                b.push_back(x);
            } else {
                a.insert(a.end(), b.rbegin(), b.rend());
                b = {x};
            }
        }
    }

    if (a.empty() || b.empty() || !are_connected(a, b)) {
        return a.size() > b.size() ? a : b;
    }

    if (size(a) < size(b)) {
        swap(a, b);
    }

    if (!are_connected(a, {b[0]}) && !are_connected(a, {b.back()})) {
        int lo = 0, hi = size(b);
        while (lo + 1 < hi) {
            int mid = lo + hi >> 1;
            if (are_connected(a, vector(b.begin(), b.begin() + mid))) {
                hi = mid;
            } else {
                lo = mid;
            }
        }
        rotate(b.begin(), b.begin() + lo, b.end());
    } else if (!are_connected(a, {b[0]})) {
        reverse(b.begin(), b.end());
    }

    assert(are_connected(a, {b[0]}));

    if (are_connected({a[0], a.back()}, {b[0]})) {
        if (are_connected({a[0]}, {b[0]})) {
            reverse(a.begin(), a.end());
        }
        a.insert(a.end(), b.begin(), b.end());
        return a;
    } else {
        int lo = 0, hi = size(a);
        while (lo + 1 < hi) {
            int mid = lo + hi >> 1;
            if (are_connected(vector(a.begin(), a.begin() + mid), {b[0]})) {
                hi = mid;
            } else {
                lo = mid;
            }
        }
        rotate(a.begin(), a.begin() + hi, a.end());
        a.insert(a.end(), b.begin(), b.end());
        return a;
    }
}

컴파일 시 표준 에러 (stderr) 메시지

longesttrip.cpp: In function 'std::vector<int> longest_trip(int, int)':
longesttrip.cpp:70:26: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   70 |             int mid = lo + hi >> 1;
      |                       ~~~^~~~
longesttrip.cpp:93:26: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   93 |             int mid = lo + hi >> 1;
      |                       ~~~^~~~

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