Submission #1168308

#	Time	Username	Problem	Language	Result	Execution time	Memory
1168308		vibeduck	Solar Storm (NOI20_solarstorm)	C++20	46 / 100	734 ms	313428 KiB

SolarStorm

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

#define pb push_back
#define pf push_front
#define mp make_pair
#define fi first
#define se second
#define int long long
#define all(x) (x).begin(), (x).end()

typedef long double ld;
typedef long long ll;
typedef pair<ll,ll> pll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<bool> vb;
typedef vector<vector<int>> vvi;
typedef vector<vector<bool>> vvb;
typedef vector<vector<ll>> vvll;
typedef vector<string> vs;
typedef vector<vector<string>> vvs;
typedef vector<char> vc;
typedef vector<vector<char>> vvc;
typedef map<int, int> mii;
typedef unordered_map<int, int> umii;

const int mod = 1e9 + 7;
const int inf = INTMAX_MAX;
const bool tc = false;

int n, s, k;
const int mxn = 1e6 + 5;
int p[mxn], vp[mxn];
pii bounds[mxn]; int up[mxn][21]; int sroot[mxn]; vi adj[mxn];

int sv(int l, int r) {
    return vp[r + 1] - vp[l];
}

int sex(int st) {
    int ans = sv(bounds[st].fi, bounds[st].se);
    if (bounds[up[st][0]].fi <= bounds[st].se) ans -= sv(bounds[up[st][0]].fi, bounds[st].se);
    return ans;
}

void dfs(int node, int prev) {
    if (node != n) sroot[node] = sroot[prev] + sex(node);
    for (auto &neighbour : adj[node]) {
        if (neighbour == prev) continue;
        dfs(neighbour, node);
    }
}

int kanc(int node, int k) {
    for (int i = 0; i < 21; i++) {
        if (k & (1 << i)) node = up[node][i];
    }
    return node;
}

inline void solve() {
    // input
    cin >> n >> s >> k;
    for (int i = 0; i < n - 1; i++) cin >> p[i + 1];
    for (int i = 1; i < n; i++) p[i] += p[i - 1];
    for (int i = 0; i < n; i++) cin >> vp[i + 1];
    for (int i = 1; i <= n; i++) vp[i] += vp[i - 1];
    
    // calculate bounds
    for (int t = 0; t < n; t++) {
        int lo = t;
        int hi = n;
        while (hi > lo + 1) {
            int mid = (lo + hi) / 2;
            if (p[mid] - p[t] > k) hi = mid;
            else lo = mid;
        }
        int r = lo;
        int l;
        if (p[t] <= k) l = 0;
        else {
            int lo = 0;
            int hi = t;
            while (hi > lo + 1) {
                int mid = (lo + hi) / 2;
                if (p[t] - p[t-mid] > k) hi = mid;
                else lo = mid;
            }
            l = t-lo;
        }
        bounds[t] = {l, r};
        //cout << t << " bounds " << l << " -> " << r << '\n';
    }

    bounds[n] = {1e18, 1e18};

    // find next segment
    for (int st = 0; st < n; st++) {
        int nxt;

        if (bounds[st].se != n - 1 && bounds[st + 1].fi <= bounds[st].se + 1) {
            int lo = st;
            int hi = n;
            while (hi > lo + 1) {
                int mid = (lo + hi) / 2;
                if (bounds[mid].fi <= bounds[st].se + 1) lo = mid;
                else hi = mid;
            }
            nxt = lo;
        } else {
            nxt = n;
        }

        up[st][0] = nxt;
    }

    for (int i = 0; i < n; i++) {
        adj[up[i][0]].pb(i);
        adj[i].pb(up[i][0]);
    }

    dfs(n, n);

    for (int i = 0; i < 21; i++) {
        up[n][i] = n;
    }

    for (int l = 1; l < 21; l++) {
        for (int i = 0; i < n; i++) {
            up[i][l] = up[up[i][l - 1]][l - 1];
        }
    }

    sroot[n] = 0;

    pii ans = {-100, -1};
    for (int i = 0; i < n; i++) {
        //cout << "look at " << i+1 << '\n';
        //cout << "direct par is " << up[i][0] + 1 << '\n';

        int high = kanc(i, s - 1);

        //cout << "max till is " << high+1 << '\n';

        pii cur = {-100, i};
        if (high == n) {
            //cout << "case1\n";
            //cout << "val: " << sroot[i] - sex(n - 1) + sv(bounds[n - 1].fi, bounds[n - 1].se) << '\n';
            cur = max(cur, {sroot[i] - sex(n - 1) + sv(bounds[n - 1].fi, bounds[n - 1].se), i});
        } else {
            //cout << "case2\n";
            //cout << sroot[i] << " - " << sroot[up[high][0]] << " - " <<  sex(high) << " + " << sv(bounds[high].fi, bounds[high].se) << '\n';
            //cout << "val: " << sroot[i] - sroot[up[high][0]] - sex(high) + sv(bounds[high].fi, bounds[high].se) << '\n';
            cur = max(cur, {sroot[i] - sroot[up[high][0]] - sex(high) + sv(bounds[high].fi, bounds[high].se), i});
        }

        //cout << i + 1 << " gave us " << cur.fi << '\n';
        //cout << '\n';
        ans = max(ans, cur);
    }
    
    vi answer; int cur = ans.se; for (int i = 0; i < s; i++) {
        if (cur == n) break;
        answer.pb(cur);
        cur = up[cur][0];
    }

    cout << answer.size() << '\n';
    for (auto &x : answer) cout << x + 1 << " ";
    cout << '\n';
}

void setIO(string s) {
    freopen((s + ".in").c_str(), "r", stdin);
    freopen((s + ".out").c_str(), "w", stdout);
}

signed main() {
    ios::sync_with_stdio(false);
    cout.tie(0);
    cin.tie(0);
    //setIO();

    int t = 1;
    if (tc) {
        cin >> t;
    }

    while (t--) {
        solve();
    }
}

Compilation message (stderr)

SolarStorm.cpp: In function 'void setIO(std::string)':
SolarStorm.cpp:176:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  176 |     freopen((s + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SolarStorm.cpp:177:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  177 |     freopen((s + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 7 / 7
• Subtask 3: 11 / 11
• Subtask 4: 0 / 8
• Subtask 5: 18 / 18
• Subtask 6: 0 / 16
• Subtask 7: 0 / 30