提出 #29700070

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ソースコード 拡げる

// #include <atcoder/all>
// using namespace atcoder;
// using mint = modint998244353;
// using mint = modint1000000007;
#include <bits/stdc++.h>
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define rep2(i,k,n) for (int i = (k); i < (n); ++i)
using namespace std;
using ll = long long;
// using P = pair<ll,ll>;
using P = pair<int,int>;
using vint = vector<int>;
using vll = vector<ll>;
using vvint = vector<vector<int>>;
using vvll = vector<vector<ll>>;

// const ll INF = (ll)2e18+9;
const int INF = (int)2e9+7;
// const ll MOD = (ll)1e9+9;
template<typename T>
void chmin(T &a, T b) { a = min(a, b); }
template<typename T>
void chmax(T &a, T b) { a = max(a, b); }

template<typename T>
void print(vector<T> v) {
    int n = v.size();
    rep(i,n) {
        if (i == 0) cout << v[i];
        else cout << ' ' << v[i];
    }
    cout << endl;
}

void solve() {
    ll n, k;
    cin >> n >> k;
    vll A(n);
    rep(i,n) cin >> A[i];

    vint used(n);
    ll pos = 0, len = 0;
    ll tot = 0;
    vll memo(n, 0);
    while (!used[pos]) {
        // cout << pos << ' ' << A[pos] << ' ' << tot << endl;
        memo[pos] = len;
        used[pos] = 1;
        tot += A[pos];
        pos = tot % n;
        len++;
    }
    ll tail = memo[pos];
    // cout << pos << ' ' << A[pos] << ' ' << len << ' ' << tail << endl;
    ll tail_pos = pos;

    ll tail_tot = 0;
    int t = tail;
    pos = 0;
    while (t) {
        tail_tot += A[pos];
        pos = tail_tot % n;
        t--;
    }
    // cout << tail_tot << endl;

    ll circle_tot = tot - tail_tot;
    ll circle_len = len - tail;
    // cout << circle_len << endl;

    if (k <= len) {
        pos = 0;
        tot = 0;
        while (k) {
            tot += A[pos];
            pos = tot % n;
            k--;
        }
        cout << tot << endl;
        return;
    }

    ll ans = tail_tot;
    k -= tail;
    ans += circle_tot * (k / circle_len);
    k -= (k / circle_len) * circle_len;

    pos = tail_pos;
    while (k) {
        ans += A[pos];
        pos = ans % n;
        k--;
    }
    cout << ans << endl;
}

int main() {
    solve();
    return 0;
}

提出情報

ジャッジ結果