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IDProblemSubmitterResultTimeMemoryLanguageFile sizeSubmit timeJudge time
#333578#8050. Random Permutationucup-team197TL 3ms20564kbC++205.4kb2024-02-20 08:40:342024-02-20 08:40:34

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你现在查看的是最新测评结果

  • [2024-02-20 08:40:34]
  • 评测
  • 测评结果:TL
  • 用时:3ms
  • 内存:20564kb
  • [2024-02-20 08:40:34]
  • 提交

answer

#include <iostream> 
#include <algorithm>
#include <array>
#include <map>
#include <set>
#include <numeric>

using namespace std;

const int N = 3e5 + 3;
const int INF = 1e9;
typedef long long ll;

int p[N], n, pos[N];
int gl[N], gr[N];
ll ans = 0;

struct SegmentTree{
    struct Node{
        int mn, mx;
        Node(){
            mn = INF;
            mx = -INF;
        }
        Node(int idx){
            mn = mx = 0;
        }

        friend Node merge(const Node &l, const Node &r){
            Node ret;
            ret.mn = min(l.mn, r.mn);
            ret.mx = max(l.mx, r.mx);
            return ret;
        }
    } nd[4 * N];
    int lp[4 * N];

    void init(int i = 0, int l = 0, int r = n){
        if(l == r){
            nd[i] = Node(l);
            return;
        }

        int mid = (l + r) >> 1;
        init(2 * i + 1, l, mid);
        init(2 * i + 2, mid + 1, r);
        nd[i] = merge(nd[2 * i + 1], nd[2 * i + 2]);
        lp[i] = 0;
    }

    void push(int i, int l, int r){
        if(!lp[i]) return;

        nd[i].mx += lp[i];
        nd[i].mn += lp[i];
        if(l != r){
            lp[2 * i + 1] += lp[i];
            lp[2 * i + 2] += lp[i];
        }
        lp[i] = 0;
    }

    void update(int sl, int sr, int val, int i = 0, int l = 0, int r = n){
        push(i, l, r);
        if(r < sl || sr < l) return;
        if(sl <= l && r <= sr){
            lp[i] += val;
            push(i, l, r);
            return;
        }
        int mid = (l + r) >> 1;
        update(sl, sr, val, 2 * i + 1, l, mid);
        update(sl, sr, val, 2 * i + 2, mid + 1, r);
        nd[i] = merge(nd[2 * i + 1], nd[2 * i + 2]);
    }

    Node query(int sl, int sr, int i = 0, int l = 0, int r = n){
        // if(sl > sr) return Node();
        if(r < sl || sr < l) return Node();
        push(i, l, r);
        if(sl <= l && r <= sr) return nd[i];

        int mid = (l + r) >> 1;
        auto l_ans = query(sl, sr, 2 * i + 1, l, mid);
        auto r_ans = query(sl, sr, 2 * i + 2, mid + 1, r);
        return merge(l_ans, r_ans);
    }
} st;

void calc_answer(){
    static int cnt2[2 * N];
    int *cnt = cnt2 + N;
    for(int i = 1; i <= n; ++i){
        int sum = 0;
        ++cnt[0];
        for(int j = pos[i] - 1; j > gl[i]; --j){
            int val = (p[j] > i) ? 1 : -1;
            sum += val;
            ++cnt[sum];
        }

        sum = 0;
        ans += ((ll)i) * (cnt[-sum] + cnt[-sum + 1]);
        for(int j = pos[i] + 1; j <= gr[i]; ++j){
            int val = (p[j] > i) ? 1 : -1;
            sum += val;
            ans += ((ll)i)*(cnt[-sum] + cnt[-sum + 1]);
        }

        {
            int sum = 0;
            --cnt[0];
            for(int j = pos[i] - 1; j > gl[i]; --j){
                int val = (p[j] > i) ? 1 : -1;
                sum += val;
                --cnt[sum];
            }
        }
    }
    cout << ans << "\n";
}

int get_g(int pos, bool dir, bool mx){
    SegmentTree::Node nd;
    if(dir == true){
        nd = st.query(pos, n);
    }
    else{
        nd = st.query(0, pos - 1);
    }

    int l, r;
    if(dir == true){
        l = 0, r = pos - 1;
    }
    else{
        l = pos, r = n;
        auto [t_min, t_max] = nd;
        nd.mn = -t_max;
        nd.mx = -t_min;
    }

    int cnt = 20;
    int ans = -1;
    for(; true; cnt *= 2){
        cnt = min(cnt, r - l + 1);

        int mid;
        if(dir) mid = pos - cnt;
        else mid = pos + cnt - 1;

        SegmentTree::Node node_mid;
        if(dir == true){
            node_mid = st.query(0, mid);
            auto [t_min, t_max] = node_mid;
            node_mid.mn = -t_max;
            node_mid.mx = -t_min;
        }
        else{
            node_mid = st.query(mid, n);
        }

        bool ok;
        if(mx == true){
            ok = (node_mid.mx + nd.mx) >= 0;
        }
        else{
            ok = (node_mid.mn + nd.mn) <= 1;
        }

        ans = mid;
        if(!ok){
            break;
        }
        if(cnt == r - l + 1) break;
    }

    return ans;
}

void calc_ranges(){
    st.init();
    for(int i = 1; i <= n; ++i)
        st.update(i, n, 1);

    for(int i = 1; i <= n / 2; ++i){
        st.update(pos[i], n, -1);
        
        int diff = abs(i - n / 2);
        if(diff > 0){
            gl[i] = get_g(pos[i], true, false);
            gr[i] = get_g(pos[i], false, false);
        }
        else{
            gl[i] = 0;
            gr[i] = n;
        }

        st.update(pos[i], n, -1);
    }

    for(int i = n / 2 + 1; i <= n; ++i){
        st.update(pos[i], n, -1);

        int diff = abs(i - n / 2);
        if(diff > 0){
            gl[i] = get_g(pos[i], true, false);
            gr[i] = get_g(pos[i], false, false);
        }
        else{
            gl[i] = 0;
            gr[i] = n;
        }

        st.update(pos[i], n, -1);
    }

    for(int i = 1; i <= n; ++i){
        // cout << gl[i] << " " << gr[i] << endl;
        // gl[i] = max(gl[i] - 1, 0);
        // gr[i] = min(gr[i] + 1, n);
        // gl[i] = 0, gr[i] = n;
    }
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(NULL);

    cin >> n;
    for(int i = 1; i <= n; ++i){
        cin >> p[i];
        pos[p[i]] = i;
    }

    // cout << "before " << endl;
    calc_ranges();
    // cout << "ranges" << endl;
    calc_answer();
}

Details

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Test #1:

score: 100
Accepted
time: 3ms
memory: 20564kb

input:

4
1 4 2 3

output:

22

result:

ok 1 number(s): "22"

Test #2:

score: -100
Time Limit Exceeded

input:

100000
56449 21738 74917 44834 36187 96576 37204 28451 3444 13029 66039 8955 51445 30706 27229 37159 66052 16691 70389 29935 44984 3648 75082 73600 76621 28345 5298 37940 49412 85260 92029 18185 84398 10233 79227 98312 96649 30680 65206 38879 75397 26951 11294 58085 37297 97167 59252 44104 4058 3796...

output:


result: