Submission #620059

#	Time	Username	Problem	Language	Result	Execution time	Memory
620059		fabijan_cikac	Exam (eJOI20_exam)	C++17	12 / 100	148 ms	32844 KiB

exam

#include <bits/stdc++.h>

using namespace std;

const int BIT = 17;
const int N = (1 << BIT);
const int INF = 1e9;

int n; int lt[N]; int rt[N];
int a[N]; int b[N]; int rmq[BIT][N];
set<int> v[2 * N];

int maks(int l, int r){
    int x = log2(r - l + 1);
    return max(rmq[x][l], rmq[x][r - (1 << x) + 1]);
}

void find_bound(){
    for (int i = 0; i < n; ++i){
        rmq[0][i] = a[i];
        lt[i] = INF; rt[i] = INF;
    }
    for (int i = 1; i < BIT; ++i){
        for (int j = 0; j <= n - (1 << i); ++j)
            rmq[i][j] = max(rmq[i - 1][j], rmq[i - 1][j + (1 << (i - 1))]);
    }
    for (int i = 0; i < n; ++i){
        if (v[b[i]].empty()) continue;
        if (a[i] == b[i]){
            lt[i] = i; rt[i] = i; continue;
        }
        auto it = v[b[i]].lower_bound(i);
        if (it != v[b[i]].end()){
            int x = (*it);
            if (maks(i, x) == b[i])
                rt[i] = x;
        }
        if (it == v[b[i]].begin()) continue;
        --it;
        int x = (*it);
        if (maks(x, i) == b[i])
            lt[i] = x;
    }
}

void compress(){
    set<int> s; int cnt = 1;
    map<int, int> mp;
    for (int i = 0; i < n; ++i){
        s.insert(a[i]); s.insert(b[i]);
    }
    for (int x: s){
        mp[x] = cnt; ++cnt;
    }
    for (int i = 0; i < n; ++i){
        a[i] = mp[a[i]]; b[i] = mp[b[i]];
    }
}

bool cluster_2(){
    for (int i = 1; i < n; ++i){
        if (b[i] != b[i - 1]) return 0;
    }
    return 1;
}

bool cluster_4(){
    set<int> s;
    for (int i = 0; i < n; ++i)
        s.insert(a[i]);
    if (s.size() != n)
        return 0;
    return 1;
}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    cin >> n;
    for (int i = 0; i < n; ++i) cin >> a[i];
    for (int i = 0; i < n; ++i) cin >> b[i];
    compress();
    for (int i = 0; i < n; ++i)
        v[a[i]].insert(i);
    find_bound();

    if (cluster_2()){
        int bio[N] = { 0 };
        queue<int> q; int ans = 0;
        for (int i = 0; i < n; ++i){
            if (a[i] == b[0]){
                q.push(i); bio[i] = 1;
            }
        }
        while (!q.empty()){
            int x = q.front(); q.pop();
            int dx[2] = {-1, 1};
            for (int i = 0; i < 2; ++i){
                int y = x + dx[i];
                if (y >= 0 && y < n && !bio[y] && a[y] <= b[0]){
                    bio[y] = 1; q.push(y);
                }
            }
        }
        for (int i = 0; i < n; ++i)
            ans += bio[i];
        cout << ans;
    }
    else if (cluster_4()){

    }
    else{
        int dp[2][N];
        for (int i = 0; i < 2; ++i){
            for (int j = 0; j <= n; ++j)
                dp[i][j] = -INF;
        }
        dp[0][0] = 0; dp[1][0] = 0;
        for (int i = 1; i <= n; ++i){
            //[0] - ulijevo ide
            if (lt[i - 1] != INF){
                dp[0][i] = 1;
                for (int j = 1; j < i; ++j){
                    if (a[j - 1] >= b[i - 1] || lt[i - 1] > j - 1)
                        dp[0][i] = max(dp[0][i], dp[0][j] + 1);
                    if (b[j - 1] < a[i - 1] && lt[i - 1] > j - 1)
                        dp[0][i] = max(dp[0][i], dp[1][j] + 1);
                    else if (b[j - 1] > a[i - 1] && rt[j - 1] < i - 1)
                        dp[0][i] = max(dp[0][i], dp[1][j] + 1);
                    else if (a[j - 1] == b[i - 1] && rt[j - 1] == i - 1)
                        dp[0][i] = max(dp[0][i], dp[1][j] + 1);
                }
            }
            //[1] - udesno
            if (rt[i - 1] != INF){
                dp[1][i] = 1;
                for (int j = 1; j < i; ++j){
                    dp[1][i] = max(dp[1][i], dp[0][j] + 1);
                    if (b[j - 1] <= a[i - 1] || rt[j - 1] < i - 1)
                        dp[1][i] = max(dp[1][i], dp[1][j] + 1);
                }
            }
        }
        int ans = 0;
        for (int i = 0; i <= n; ++i)
            ans = max(ans, max(dp[0][i], dp[1][i]));
        cout << ans;
    }

    return 0;
}

Compilation message (stderr)

exam.cpp: In function 'bool cluster_4()':
exam.cpp:71:18: warning: comparison of integer expressions of different signedness: 'std::set<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   71 |     if (s.size() != n)
      |         ~~~~~~~~~^~~~

• Subtask 1: 0 / 14
• Subtask 2: 12 / 12
• Subtask 3: 0 / 13
• Subtask 4: 0 / 23
• Subtask 5: 0 / 16
• Subtask 6: 0 / 22