Submission #537240

#	Time	Username	Problem	Language	Result	Execution time	Memory
537240		surgutti	Martian DNA (BOI18_dna)	C++14	100 / 100	124 ms	139472 KiB

dna

#include <bits/stdc++.h>

using namespace std;

const int N = 200'007;

int n, s, r, d[N], b[N], q[N];

int req[N], nxt_req[N];
int nxt[N], cur_req[N];

queue<int> last[N];

int main() {
    ios::sync_with_stdio(false), cin.tie(nullptr);
    
    cin >> n >> s >> r;

    for (int i = 0; i < n; i++) {
        cin >> d[i];

        cur_req[i] = -1;
    }

    for (int i = 0; i < r; i++) {
        cin >> b[i] >> q[i];
        req[b[i]] = q[i];
    }

    for (int i = n - 1; i >= 0; i--) if (req[d[i]] > 0) {
        
        if ((int) last[d[i]].size() > 0) {
            nxt[i] = last[d[i]].back();
        }
        else {
            nxt[i] = -1;
        }

        last[d[i]].push(i);

        if ((int) last[d[i]].size() > req[d[i]]) {
            last[d[i]].pop();
        }

        if ((int) last[d[i]].size() < req[d[i]]) {
            nxt_req[i] = -1;
        }
        else {
            nxt_req[i] = last[d[i]].front();
        }
    }

    int ans = INT_MAX, req_done = 0;
    
    for (int i = 0, j = -1, k = -1; i < n; i++) {
        
        while (j + 1 < n && req_done < r) {
            j++;

            if (req[d[j]] > 0 && cur_req[d[j]] == -1 && nxt_req[j] != -1) {
                cur_req[d[j]] = j;
                k = max(k, nxt_req[j]);
                req_done++;
            }
        }
        
        if (req_done == r) {
            ans = min(ans, k - i + 1);
        }
        else {
            break;
        }

        if (req[d[i]] > 0) {
            cur_req[d[i]] = -1;
            req_done--;
            if (nxt[i] <= j && nxt[i] != -1 && nxt_req[nxt[i]] != -1) {
                cur_req[d[i]] = nxt[i];
                k = max(k, nxt_req[nxt[i]]);
                req_done++;       
            }
        }
    }

    if (ans == INT_MAX) {
        cout << "impossible\n";
    }
    else {
        cout << ans << '\n';
    }
}

• Subtask 1: 16 / 16
• Subtask 2: 24 / 24
• Subtask 3: 28 / 28
• Subtask 4: 32 / 32