Submission #993383

#	Time	Username	Problem	Language	Result	Execution time	Memory
993383		vladilius	Fire (BOI24_fire)	C++17	100 / 100	165 ms	64076 KiB

Main

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
#define pb push_back
#define ff first
#define ss second
#define ins insert

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    
    int n, m; cin>>n>>m;
    vector<int> l(n + 1), r(n + 1);
    for (int i = 1; i <= n; i++){
        cin>>l[i]>>r[i];
        if (!r[i]) r[i] = m;
        r[i]--;
        if (l[i] > r[i]){
            r[i] += m;
        }
    }
    
    vector<pii> all;
    for (int i = 1; i <= n; i++){
        all.pb({l[i], r[i]});
    }
    sort(all.begin(), all.end());
    vector<pii> tmp;
    int i = 0;
    while (i < n){
        int j = i;
        while (j < n && all[i].ff == all[j].ff){
            j++;
        }
        tmp.pb({all[j - 1].ss, all[j - 1].ff});
        i = j;
    }
    all = tmp;
    sort(all.begin(), all.end());
    tmp.clear();
    i = 0;
    while (i < all.size()){
        int j = i;
        while (j < all.size() && all[i].ff == all[j].ff){
            j++;
        }
        tmp.pb({all[i].ss, all[i].ff});
        i = j;
    }
    all = tmp;
    
    sort(all.begin(), all.end());
    n = (int) all.size();
    vector<int> log(n + 1);
    for (int i = 2; i <= n; i++){
        log[i] = log[i / 2] + 1;
    }
    const int lg = log[n];
    vector<vector<pii>> sp(n, vector<pii>(lg + 1));
    for (int i = 0; i < n; i++){
        sp[i][0] = {all[i].ss, i};
    }
    for (int k = 1; k <= lg; k++){
        for (int i = 0; i + (1 << k) <= n; i++){
            sp[i][k] = max(sp[i][k - 1], sp[i + (1 << (k - 1))][k - 1]);
        }
    }
    
    auto get = [&](int l, int r){
        int k = log[r - l + 1];
        return max(sp[l][k], sp[r - (1 << k) + 1][k]);
    };
    
    vector<int> ls;
    for (int i = 0; i < n; i++){
        ls.pb(all[i].ff);
    }
    vector<int> :: iterator it1, it2;
    
    vector<int> g(n);
    for (int i = 0; i < n; i++){
        auto &[l, r] = all[i];
        it1 = lower_bound(ls.begin(), ls.end(), l);
        it2 = upper_bound(ls.begin(), ls.end(), r + 1); it2--;
        int lb = max(i + 1, (int) (it1 - ls.begin())), rb = (int) (it2 - ls.begin());
        if (lb > rb){
            g[i] = -1;
            continue;
        }
        g[i] = get(lb, rb).ss;
        if (all[g[i]].ss <= r) g[i] = -1;
    }
    
    vector<vector<int>> pw(n, vector<int>(lg + 1, -1));
    for (int i = 0; i < n; i++){
        pw[i][0] = g[i];
    }
    for (int k = 1; k <= lg; k++){
        for (int i = 0; i + (1 << k) <= n; i++){
            if (pw[i][k - 1] == -1) continue;
            pw[i][k] = pw[pw[i][k - 1]][k - 1];
        }
    }
    
    int ans = n + 1;
    for (int i = 0; i < n; i++){
        int rr = all[i].ff + m - 1, j = i, out = 1;
        for (int k = lg; k >= 0; k--){
            int v = pw[j][k];
            if (v != -1 && all[v].ss <= rr){
                j = v;
                out += (1 << k);
            }
        }
        while (j != -1 && all[j].ss < rr){
            j = g[j]; out++;
        }
        if (j != -1) ans = min(ans, out);
    }
    cout<<((ans > n) ? -1 : ans)<<"\n";
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:45:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   45 |     while (i < all.size()){
      |            ~~^~~~~~~~~~~~
Main.cpp:47:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   47 |         while (j < all.size() && all[i].ff == all[j].ff){
      |                ~~^~~~~~~~~~~~

• Subtask 1: 14 / 14
• Subtask 2: 17 / 17
• Subtask 3: 9 / 9
• Subtask 4: 13 / 13
• Subtask 5: 21 / 21
• Subtask 6: 26 / 26