Submission #689942

#	Time	Username	Problem	Language	Result	Execution time	Memory
689942		Patrick	Race (IOI11_race)	C++17	21 / 100	117 ms	7628 KiB

race

#include "race.h"

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

typedef long long ll;

unordered_map<ll, int> solve(int N, int K, vector<vector<pair<int, int>>>& es,
                             int& curmin, int last, int cur) {
    // cout << "solve " << cur << "\n";
    unordered_map<ll, int> ans;
    ans.insert({0, 0});

    for (auto [next, len] : es[cur]) {
        if (next == last) continue;
        unordered_map<ll, int> a = solve(N, K, es, curmin, cur, next);

        for (auto [k, v] : a) {
            if (k > K) continue;
            int search = K - (k + len);
            auto it = ans.find(search);
            if (it != ans.end()) {
                curmin = min(curmin, it->second + v + 1);
            }
        }
        for (auto [k, v] : a) {
            if (k > K) continue;
            ans.insert({k + len, v + 1});
        }
    }
    return ans;
}

int best_path(int N, int K, int H[][2], int L[]) {
    // cout << "testcase\n";
    vector<vector<pair<int, int>>> es(N);
    for (int i = 0; i < N - 1; i++) {
        es[H[i][0]].push_back({H[i][1], L[i]});
        es[H[i][1]].push_back({H[i][0], L[i]});
    }
    int curmin = N;
    auto ans = solve(N, K, es, curmin, -1, 0);
    if (curmin == N) {
        return -1;
    } else {
        return curmin;
    }
}

• Subtask 1: 9 / 9
• Subtask 2: 12 / 12
• Subtask 3: 0 / 22
• Subtask 4: 0 / 57