Submission #1334065

#TimeUsernameProblemLanguageResultExecution timeMemory
1334065kawhietHorses (IOI15_horses)C++20
17 / 100
186 ms33696 KiB
#include <bits/stdc++.h>
#include "horses.h"
using namespace std;

using i64 = long long;

constexpr int mod = 1e9 + 7;

struct SegmentTree {
    int n;
    vector<i64> t;

    void init(int _n) {
        n = _n;
        t.assign(4 * n, 1);
    }

    void update(int id, int tl, int tr, int i, i64 v) {
        if (tl == tr) {
            t[id] = v;
            return;
        }
        int x = (id << 1) + 1, y = x + 1, tm = (tl + tr) >> 1;
        if (i <= tm) {
            update(x, tl, tm, i, v);
        } else {
            update(y, tm + 1, tr, i, v);
        }
        t[id] = t[x] * t[y] % mod;
    }

    i64 get(int id, int tl, int tr, int l, int r) {
        if (r < tl || tr < l) return 1;
        if (l <= tl && tr <= r) return t[id];
        int x = (id << 1) + 1, y = x + 1, tm = (tl + tr) >> 1;
        return get(x, tl, tm, l, r) * get(y, tm + 1, tr, l, r) % mod;
    }

    void update(int i, int v) { update(0, 0, n - 1, i, v); }
    int get(int l, int r) { return get(0, 0, n - 1, l, r); }
};

struct FenwickTree {
    int n;
    vector<int> bit;

    void init(int _n) {
        n = _n;
        bit.resize(n + 1);
    }

    void update(int k, int d) {
        k++;
        for (; k <= n; k += k & -k) {
            bit[k] += d;
        }
    }

    int get(int k) {
        k++;
        int ret = 0;
        for (; k >= 1; k -= k & -k) {
            ret += bit[k];
        }
        return ret;
    }

    int get(int l, int r) {
        l++; r++;
        return get(r) - get(l - 1);
    }
};

int n;
SegmentTree t;
FenwickTree cnt;
vector<int> x, y;

bool is(int l, int r) {
    i64 k = y[r];
    for (int i = l + 1; i <= r; i++) {
        k *= x[i];
        if (k > y[l]) {
            return true;
        }
    }
    return false;
}

int solve() {
    int st = max(0, n - 1000);
    int pos = st;
    i64 ans = t.get(0, pos) * y[pos] % mod;
    vector<i64> p(n), a(n);
    p[0] = x[0];
    a[0] = x[0] * y[0] % mod;
    for (int i = 1; i < n; i++) {
        p[i] = p[i - 1] * x[i] % mod;
        a[i] = p[i] * y[i] % mod;
        assert(p[i] == t.get(0, i));
    }
    for (int i = st; i < n; i++) {
        if (is(pos, i)) {
            pos = i;
            ans = t.get(0, i) * y[i] % mod;
            assert(ans == a[i]);
        }
    }
    return ans;
}

int init(int N, int X[], int Y[]) {
    n = N;
    x.assign(X, X + N);
    y.assign(Y, Y + N);
    t.init(n);
    cnt.init(n);
    for (int i = 0; i < n; i++) {
        t.update(i, x[i]);
        if (x[i] > 1) {
            cnt.update(i, 1);
        }
    }
    return solve();
}

int updateX(int pos, int val) {
    if (x[pos] > 1) {
        cnt.update(pos, -1);
    }
    if (val > 1) {
        cnt.update(pos, 1);
    }
    t.update(pos, val);
    x[pos] = val;
    return solve();
}

int updateY(int pos, int val) {
    y[pos] = val;
    return solve();
}
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