Submission #943624

#	Time	Username	Problem	Language	Result	Execution time	Memory
943624		Pannda	Fish 2 (JOI22_fish2)	C++17	8 / 100	1677 ms	13464 KiB

fish2

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

struct Paint {
    struct Node {
        int mn, cnt;
        int lazy = 0;
        void add(int delta) {
            mn += delta;
            lazy += delta;
        }
        void merge(Node a, Node b) {
            mn = min(a.mn, b.mn);
            cnt = 0;
            if (a.mn == mn) cnt += a.cnt;
            if (b.mn == mn) cnt += b.cnt;
        }
    };

    int n;
    vector<Node> nodes;

    Paint(int n) : n(n), nodes(4 * n) {
        auto dfs = [&](auto self, int idx, int l, int r) -> void {
            if (l + 1 == r) {
                nodes[idx].mn = 0;
                nodes[idx].cnt = 1;
            } else {
                int m = (l + r) >> 1;
                self(self, 2 * idx + 1, l, m);
                self(self, 2 * idx + 2, m, r);
                nodes[idx].merge(nodes[2 * idx + 1], nodes[2 * idx + 2]);
            }
        };
        dfs(dfs, 0, 0, n);
    }

    void down(int idx) {
        nodes[2 * idx + 1].add(nodes[idx].lazy);
        nodes[2 * idx + 2].add(nodes[idx].lazy);
        nodes[idx].lazy = 0;
    }

    void add(int ql, int qr, int delta) {
        auto dfs = [&](auto self, int idx, int l, int r) -> void {
            if (r <= ql || qr <= l) return;
            if (ql <= l && r <= qr) return nodes[idx].add(delta);
            down(idx);
            int m = (l + r) >> 1;
            self(self, 2 * idx + 1, l, m);
            self(self, 2 * idx + 2, m, r);
            nodes[idx].merge(nodes[2 * idx + 1], nodes[2 * idx + 2]);
        };
        dfs(dfs, 0, 0, n);
    }

    int countZero(int ql, int qr) {
        int fetch = 0;
        auto dfs = [&](auto self, int idx, int l, int r) -> void {
            if (r <= ql || qr <= l) return;
            if (ql <= l && r <= qr) {
                fetch += nodes[idx].mn == 0 ? nodes[idx].cnt : 0;
                return;
            }
            down(idx);
            int m = (l + r) >> 1;
            self(self, 2 * idx + 1, l, m);
            self(self, 2 * idx + 2, r, m);
        };
        dfs(dfs, 0, 0, n);
        return fetch;
    }
};

struct SegmentWalk {
    int n;
    vector<int> mx;

    SegmentWalk(int n) : n(n), mx(4 * n, 0) {}

    void set(int i, int val) {
        auto dfs = [&](auto self, int idx, int l, int r) -> void {
            if (l + 1 == r) {
                mx[idx] = val;
            } else {
                int m = (l + r) >> 1;
                if (i < m) self(self, 2 * idx + 1, l, m);
                else self(self, 2 * idx + 2, m, r);
                mx[idx] = max(mx[2 * idx + 1], mx[2 * idx + 2]);
            }
        };
        dfs(dfs, 0, 0, n);
    }

    int walk(int ql, int qr, long long bound, bool request_leftmost) { // in [ql, qr), returns the leftmost (rightmost) position with value > 'bound'
        auto dfs = [&](auto self, int idx, int l, int r) -> int {
            if (r <= ql || qr <= l || mx[idx] <= bound) return -1;
            if (ql <= l && r <= qr) {
                while (l + 1 < r) {
                    int m = (l + r) >> 1;
                    if (request_leftmost) {
                        if (mx[2 * idx + 1] > bound) idx = 2 * idx + 1, r = m;
                        else idx = 2 * idx + 2, l = m;
                    } else {
                        if (mx[2 * idx + 2] > bound) idx = 2 * idx + 2, l = m;
                        else idx = 2 * idx + 1, r = m;
                    }
                }
                return l;
            }
            int m = (l + r) >> 1;
            if (request_leftmost) {
                int get = self(self, 2 * idx + 1, l, m);
                if (get != -1) return get;
                return self(self, 2 * idx + 2, m, r);
            } else {
                int get = self(self, 2 * idx + 2, m, r);
                if (get != -1) return get;
                return self(self, 2 * idx + 1, l, m);
            }
        };
        return dfs(dfs, 0, 0, n);
    }
};

struct Fenwick {
    int n;
    vector<long long> bit;

    Fenwick(int n) : n(n), bit(n + 1, 0) {}

    void add(int i, int delta) {
        for (i++; i <= n; i += i & -i) bit[i] += delta;
    }

    long long sum(int i) {
        long long res = 0;
        for (; i > 0; i -= i & -i) res += bit[i];
        return res;
    }

    long long sum(int l, int r) {
        return sum(r) - sum(l);
    }
};

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    cin >> n;

    vector<int> a(n);
    Fenwick fen(n);
    SegmentWalk segwalk(n);

    for (int i = 0; i < n; i++) {
        cin >> a[i];
        fen.add(i, a[i]);
        segwalk.set(i, a[i]);
    }

    auto findSaturatedInterval = [&](int ql, int qr, int &l, int &r, long long &sum) -> void { // O(log^2), find the tightest saturated interval (or [l, r)) containing the initial interval [l, r)
        while (ql < l || r < qr) {
            long long old_sum = sum;
            if (ql < l) {
                int p = segwalk.walk(ql, l, sum, false);
                if (p == -1) {
                    sum += fen.sum(ql, l);
                    l = ql;
                } else {
                    sum += fen.sum(p + 1, l);
                    l = p + 1;
                    if (sum >= a[p]) {
                        sum += a[p];
                        l = p;
                    }
                }
            }
            if (r < qr) {
                int p = segwalk.walk(r, qr, sum, true);
                if (p == -1) {
                    sum += fen.sum(r, qr);
                    r = n;
                } else {
                    sum += fen.sum(r, p);
                    r = p;
                    if (sum >= a[p]) {
                        sum += a[p];
                        r = p + 1;
                    }
                }
            }
            if (sum == old_sum) break;
        }
    };

    auto findAllSaturatedIntervals = [&](int ql, int qr, int i) -> vector<array<int, 2>> { // O(log^2), find all saturated intervals containing i
        vector<array<int, 2>> res;
        int l = i, r = i + 1;
        long long sum = a[i];
        while (true) {
            findSaturatedInterval(ql, qr, l, r, sum);
            if (l == ql && r == qr) break;
            res.push_back({l, r});
            if (l == ql || (r < qr && a[r] <= a[l - 1])) {
                sum += a[r];
                r = r + 1;
            } else {
                sum += a[l - 1];
                l = l - 1;
            }
        }
        return res;
    };

    Paint paint(n);
    set<array<int, 2>> saturated_intervals;
    for (int i = 0; i < n; i++) {
        int l = i, r = i + 1;
        long long sum = a[i];
        findSaturatedInterval(0, n, l, r, sum);
        if (array<int, 2>{l, r} != array<int, 2>{0, n}) {
            if (!saturated_intervals.count({l, r})) {
                saturated_intervals.insert({l, r});
                paint.add(l, r, +1);
            }
        }
    }

    int q;
    cin >> q;
    while (q--) {
        int type;
        cin >> type;
        if (type == 1) {
            int i, x;
            cin >> i >> x;
            i--;
            fen.add(i, -a[i] + x);
            a[i] = x;
            segwalk.set(i, x);

            auto erase = [&](int i) { // erase from paint all intervals containing i
                if (i < 0 || i >= n) return;
                while (!saturated_intervals.empty()) {
                    auto it = saturated_intervals.lower_bound(array<int, 2>{i + 1, -1});
                    if (it == saturated_intervals.begin()) break;
                    --it;
                    auto [l, r] = *it;
                    if (r <= i) break;
                    saturated_intervals.erase(it);
                    paint.add(l, r, -1);
                }
            };

            auto add = [&](int i) { // add to paint all intervals containing i
                if (i < 0 || i >= n) return;
                vector<array<int, 2>> fetch = findAllSaturatedIntervals(0, n, i);
                for (auto [l, r] : fetch) {
                    if (!saturated_intervals.count({l, r})) {
                        saturated_intervals.insert({l, r});
                        paint.add(l, r, +1);
                    }
                }
            };

            erase(i);
            erase(i - 1);
            erase(i + 1);
            add(i);
            add(i - 1);
            add(i + 1);
        }
        if (type == 2) {
            int l, r;
            cin >> l >> r;
            l--;

            // assumes l = 0 and r = n
            cout << paint.countZero(0, n) << '\n';
        }
    }
}

• Subtask 1: 0 / 5
• Subtask 2: 8 / 8
• Subtask 3: 0 / 12
• Subtask 4: 0 / 23
• Subtask 5: 0 / 35
• Subtask 6: 0 / 17