Submission #607568

#	Time	Username	Problem	Language	Result	Execution time	Memory
607568		yanndev	Toy Train (IOI17_train)	C++17	100 / 100	1190 ms	1108 KiB

train

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

const int MX = 5042;

int n;
int deg[MX];
bool vis[MX];
bool vis2[MX];
bool isOk[MX];
bool isAlice[MX];
bool isCharge[MX];
vector<int> rgraph[MX];

bool BFS() {
    queue<int> nxt {};
    for (int i = 0; i < n; i++)
        deg[i] = 0;
    for (int i = 0; i < n; i++) {
        for (auto& x: rgraph[i])
            deg[x]++;
        if (isCharge[i] && isOk[i])
            nxt.push(i);
        vis[i] = vis2[i] = false;
    }

    //cout << layer << ' ' << (int)nxt.size() << '\n';
    
    while (!nxt.empty()) {
        auto cur = nxt.front();
        //cout << "cur is " << cur << '\n';
        nxt.pop();

        if (vis[cur])
            continue;
        vis[cur] = true;

        for (auto& x: rgraph[cur]) {
            if (!vis2[x] && ((--deg[x] == 0) || isAlice[x])) {
                vis2[x] = true;
                nxt.push(x);
            }
        }
    }

    for (int i = 0; i < n; i++) {
        if (isOk[i] && !vis2[i]) {
            isOk[i] = false;
            return true;
        }
    }

    return false;
}

vector<int> who_wins(vector<int> a, vector<int> r, vector<int> u, vector<int> v) {
    n = (int)a.size();

    for (int i = 0; i < (int)u.size(); i++)
        rgraph[v[i]].push_back(u[i]);
    
    for (int i = 0; i < n; i++) {
        isAlice[i] = a[i];
        isCharge[i] = r[i];
        isOk[i] = true;
    }

    while (BFS());

    vector<int> ans (n);
    for (int i = 0; i < n; i++)
        ans[i] = isOk[i];
    return ans;
}

/*int main() {
    for (auto& x: who_wins({0, 1}, {1, 0}, {0, 0, 1, 1}, {0, 1, 0, 1}))
        cout << x << ' ';
}*/

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