Submission #21984516

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Source Code Expand

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

int main() {
    int N = 0;
    cin >> N;

    vector<int> A(N);
    for (int i = 0; i < N; i++) cin >> A.at(i);

    int pos = 0, pressCount = 0;
    vector<int> pressedButtonMemo;

    while (true) {
        if (pos == 1) {
            cout << pressCount << endl;
            return 0;
        }

        if (find(pressedButtonMemo.begin(), pressedButtonMemo.end(), pos) != pressedButtonMemo.end()) {
            cout << -1 << endl;
            return 0;
        }

        pressedButtonMemo.push_back(pos);
        pos = A.at(pos) - 1;
        pressCount++;
    }
}

Submission Info

Judge Result