Submission #575405

#	Time	Username	Problem	Language	Result	Execution time	Memory
575405		KoD	Toy Train (IOI17_train)	C++17	100 / 100	1050 ms	1720 KiB

train

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

using ll = long long;

using std::vector;
using std::array;
using std::pair;
using std::tuple;

vector<int> who_wins(vector<int> a, vector<int> r, vector<int> u, vector<int> v) {
    const int n = (int)a.size();
    const int m = (int)u.size();
    vector<int> ret(n, -1);
    vector<vector<int>> graph(n), rev_graph(n);
    for (int i = 0; i < m; ++i) {
        graph[u[i]].push_back(v[i]);
        rev_graph[v[i]].push_back(u[i]);
    }

    const auto expand = [&](vector<char>& set, const int side) {
        vector<int> deg(n);
        std::queue<int> que;
        for (int u = 0; u < n; ++u) {
            for (const int v : graph[u]) {
                if (ret[v] == -1) {
                    deg[u] += 1;
                }
            }
            if (set[u]) {
                que.push(u);
            }
        }
        while (!que.empty()) {
            const int u = que.front();
            que.pop();
            for (const int v : rev_graph[u]) {
                if (ret[v] != -1 or set[v]) {
                    continue;
                }
                if (a[v] == side) {
                    set[v] = true;
                    que.push(v);
                } else {
                    deg[v] -= 1;
                    if (deg[v] == 0) {
                        set[v] = true;
                        que.push(v);
                    }
                }
            }
        }
    };

    while (true) {
        if (std::all_of(ret.begin(), ret.end(), [&](const int x) { return x != -1; })) {
            return ret;
        }
        
        vector<char> A_set(n);
        for (int u = 0; u < n; ++u) {
            if (ret[u] == -1 and r[u]) {
                A_set[u] = true;
            }
        }
        expand(A_set, 1);
        bool A_win = true;
        for (int u = 0; u < n; ++u) {
            if (ret[u] == -1 and !A_set[u]) {
                A_win = false;
                break;
            }
        }

        if (A_win) {
            for (int u = 0; u < n; ++u) {
                if (A_set[u]) {
                    ret[u] = 1;
                }
            }
        } else {
            vector<char> B_set(n);
            for (int u = 0; u < n; ++u) {
                if (ret[u] == -1 and !A_set[u]) {
                    B_set[u] = true;
                }
            }
            expand(B_set, 0);
            for (int u = 0; u < n; ++u) {
                if (B_set[u]) {
                    ret[u] = 0;
                }
            }
        }
    }
}

• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 11 / 11
• Subtask 4: 11 / 11
• Subtask 5: 12 / 12
• Subtask 6: 51 / 51