oj.uz

Submission #1087860

# Submission time Handle Problem Language Result Execution time Memory
1087860 2024-09-13T10:27:42 Z PanosPask Zoltan (COCI16_zoltan) C++14
140 / 140
 266 ms 19912 KB 
#include <bits/stdc++.h>
#define mp make_pair
#define pb push_back

using namespace std;

typedef long long ll;
typedef pair<int, int> pi;
typedef pair<int, ll> pil;

const int MOD = 1e9 + 7;

struct SegTree {
    struct Node {
        int len;
        ll cnt;
    };
    Node DEFAULT = {0, 1};

    Node merge(Node a, Node b) {
        Node res;
        res.len = max(a.len, b.len);
        
        res.cnt = 0;
        if (res.len == a.len) {
            res.cnt += a.cnt;
        }
        if (res.len == b.len) {
            res.cnt += b.cnt;
        }
        res.cnt %= MOD;

        return res;
    }

    int size;
    vector<Node> tree;

    void init(int N) {
        size = 1;
        while (size < N) {
            size *= 2;
        }

        tree.assign(2 * size, DEFAULT);
    }

    void improve(int i, Node v, int x, int lx, int rx) {
        if (lx == rx - 1) {
            tree[x] = merge(tree[x], v);
            return;
        }

        int mid = (lx + rx) / 2;
        if (i < mid) {
            improve(i, v, 2 * x + 1, lx, mid);
        }
        else {
            improve(i, v, 2 * x + 2, mid, rx);
        }

        tree[x] = merge(tree[2 * x + 1], tree[2 * x + 2]);
    }
    void improve(int i, pil v) {
        improve(i, {v.first, v.second}, 0, 0, size);
    }

    Node calc(int l, int r, int x, int lx, int rx) {
        if (l >= rx || lx >= r) {
            return DEFAULT;
        }
        else if (l <= lx && rx <= r) {
            return tree[x];
        }

        int mid = (lx + rx) / 2;
        return merge(calc(l, r, 2 * x + 1, lx, mid), calc(l, r, 2 * x + 2, mid, rx));
    }
    pil calc(int l, int r) {
        Node res = calc(l, r, 0, 0, size);
        return mp(res.len, res.cnt);
    }
};

int N;
vector<int> A;
SegTree st;

vector<int> cords;
vector<ll> pow2;

// increasing[i]/decreasing[i]:
// The longest strictly increasing and decreasing subsequences starting at i and the number of ways to get them
vector<pil> increasing;
vector<pil> decreasing;

int ans = 0;
ll total = 0;

int pos(int x)
{
    return lower_bound(cords.begin(), cords.end(), x) - cords.begin();
}

int main(void)
{
    scanf("%d", &N);

    A.resize(N);
    pow2.resize(N + 1);
    increasing.resize(N);
    decreasing.resize(N);

    pow2[0] = 1;
    for (int i = 0; i < N; i++) {
        scanf("%d", &A[i]);
        cords.pb(A[i]);

        pow2[i + 1] = pow2[i] * 2 % MOD;
    }
    sort(cords.begin(), cords.end());
    cords.resize(unique(cords.begin(), cords.end()) - cords.begin());

    st.init(N);
    for (int i = N - 1; i >= 0; i--) {
        increasing[i] = st.calc(pos(A[i]) + 1, N);
        increasing[i].first++;
        if (increasing[i].first == 1) {
            increasing[i].second = 1;
        }
        st.improve(pos(A[i]), increasing[i]);
    }
    st.init(N);
    for (int i = N - 1; i >= 0; i--) {
        decreasing[i] = st.calc(0, pos(A[i]));
        decreasing[i].first++;
        if (decreasing[i].first == 1) {
            decreasing[i].second = 1;
        }
        st.improve(pos(A[i]), decreasing[i]);
    }

    ans = 0;
    total = 0;
    for (int i = 0; i < N; i++) {
        int len = increasing[i].first + decreasing[i].first - 1;

        if (len > ans) {
            total = 0;
            ans = len;
        }
        if (len == ans) {
            // First find the number of possible sequences
            ll sequences = increasing[i].second * decreasing[i].second % MOD;

            // The excluded elements can be placed arbitrarily
            int excluded = N - len;
            ll ways = pow2[excluded];

            total += sequences * ways % MOD;
            total %= MOD;
        }
    }

    printf("%d %lld\n", ans, total);

    return 0;
}

Compilation message

zoltan.cpp: In function 'int main()':
zoltan.cpp:107:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  107 |     scanf("%d", &N);
      |     ~~~~~^~~~~~~~~~
zoltan.cpp:116:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  116 |         scanf("%d", &A[i]);
      |         ~~~~~^~~~~~~~~~~~~

Subtask #1
140.0 / 140.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 348 KB Output is correct
2 Correct 1 ms 348 KB Output is correct
3 Correct 0 ms 348 KB Output is correct
4 Correct 1 ms 348 KB Output is correct
5 Correct 0 ms 432 KB Output is correct
6 Correct 0 ms 348 KB Output is correct
7 Correct 1 ms 348 KB Output is correct
8 Correct 1 ms 348 KB Output is correct
9 Correct 1 ms 448 KB Output is correct
10 Correct 1 ms 348 KB Output is correct
11 Correct 152 ms 17316 KB Output is correct
12 Correct 131 ms 16076 KB Output is correct
13 Correct 119 ms 11724 KB Output is correct
14 Correct 172 ms 16572 KB Output is correct
15 Correct 230 ms 18372 KB Output is correct
16 Correct 266 ms 19912 KB Output is correct
17 Correct 183 ms 19408 KB Output is correct
18 Correct 193 ms 19284 KB Output is correct
19 Correct 190 ms 19396 KB Output is correct
20 Correct 184 ms 19228 KB Output is correct