提出 #71491407

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ソースコード 拡げる

#include <bits/stdc++.h>

#include <atcoder/all>

using namespace std;
using namespace atcoder;

#define int long long
#define ALL(x) (x).begin(), (x).end()
#define MAX(x) *max_element(ALL(x))
#define MIN(x) *min_element(ALL(x))

typedef pair<int, int> PI;
typedef pair<int, pair<int, int>> PII;
static const int INF = 1010000000000000017LL;
static const double eps = 1e-12;
static const double pi = 3.14159265358979323846;
static const int dx[4] = {1, -1, 0, 0};
static const int dy[4] = {0, 0, 1, -1};
static const int ddx[8] = {1, -1, 0, 0, 1, 1, -1, -1};
static const int ddy[8] = {0, 0, 1, -1, 1, -1, 1, -1};

template <class T>
inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template <class T>
inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

int N;

signed main() {
    cin >> N;
    vector<int> A(N + 1);
    vector<int> B(N + 5);
    for (int i = 1; i <= N; ++i) {
        cin >> A[i];
        B[i] = A[i] + i - 1;
    }
    auto op = [](int a, int b) { return max(a, b); };
    auto e = []() { return -INF; };
    segtree<int, op, e> seg(B);
    int k = 1;
    while (k <= N) {
        int h = A[k];
        int r = k + h - 1;
        int ma = seg.prod(1, r + 1);
        // cout << "r: " << r << endl;
        // cout << "ma: " << ma << endl;
        if (ma == k || ma >= N) {
            k = ma;
            break;
        }
        k = ma;
    }
    int ans = min(k, N);
    cout << ans << endl;
}

提出情報

ジャッジ結果