Submission #1298564

#	Time	Username	Problem	Language	Result	Execution time	Memory
1298564		nqc	Martian DNA (BOI18_dna)	C++20	100 / 100	54 ms	12992 KiB

dna

#include<bits/stdc++.h>
using namespace std;

#define fi first
#define se second
#define ll long long
#define ull unsigned long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define pli pair<ll, int>
#define debug(x) cout << #x << " = " << x << '\n'
#define all(a) a.begin(), a.end()
#define SZ(a) (int)(a).size()

const int N = 2e5 + 5;
const int mod = 1e9 + 7;
const ll inf64 = 3e18;
const int inf32 = 2e9 + 5;

struct FenwickTree {
    const static int LG = 18;
    int n;
    vector<int> node;

    FenwickTree() {}
    FenwickTree(int n) : n(n), node(n + 3, 0) {}

    void upd(int i, int x) {
        for(; i <= n; i += i & (-i)) 
            node[i] += x;
    }

    int get(int i) {
        int res = 0;
        for(; i; i -= i & (-i)) 
            res += node[i];
        return res;
    }
    int get(int l, int r) { return (l <= r ? get(r) - get(l - 1) : 0); }

    int walk() {
        int pos = 0;
        for(int i = LG - 1; i >= 0; i--) {
            if(pos + (1 << i) < n && node[pos + (1 << i)] == 0) 
                pos += (1 << i);
        }
        return pos + 1;
    }
};  

int n, k, m, a[N];
vector<int> pos[N];
int req[N];

void solve() {
    cin >> n >> k >> m;
    for(int i = 1; i <= n; i++) {
        cin >> a[i];
        pos[a[i]].push_back(i);
    }
    for(int i = 1, x, y; i <= m; i++) {
        cin >> x >> y;
        req[x] = y; 
    }

    int ans = n + 1;
    FenwickTree fen(n);
    for(int i = 1; i <= n; i++) {
        if(req[a[i]]) {
            int it = lower_bound(all(pos[a[i]]), i) - pos[a[i]].begin();
            if(it - req[a[i]] + 1 >= 0) {
                it += 1 - req[a[i]];
                fen.upd(pos[a[i]][it], 1);
                if(it > 0) fen.upd(pos[a[i]][it - 1], -1);
            }
        }

        int l = fen.walk();
        if(fen.get(l, i) == m) ans = min(ans, i - l + 1);
    }
    if(ans > n) cout << "impossible";
    else cout << ans << '\n';
}

int main() {
    auto start = chrono::steady_clock::now();

    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    if(fopen("input.txt", "r")) {
        freopen("input.txt", "r", stdin);
        freopen("output.txt", "w", stdout);
    }
    int test = 1; 
    // cin >> test;
    while(test--) solve();
    
    chrono::duration<double> elapsed {chrono::steady_clock::now() - start};
    cerr << "\n>> Runtime: " << elapsed.count() << "s\n";
}

Compilation message (stderr)

dna.cpp: In function 'int main()':
dna.cpp:90:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   90 |         freopen("input.txt", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
dna.cpp:91:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   91 |         freopen("output.txt", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

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