Submission #964619

#	Time	Username	Problem	Language	Result	Execution time	Memory
964619		fve5	Seats (IOI18_seats)	C++17	100 / 100	2156 ms	117804 KiB

seats

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

typedef int i64;

struct Info {
    i64 mi;
    int cnt;
};

Info merge(const Info &a, const Info &b) {
    if (a.mi < b.mi)
        return a;
    if (b.mi < a.mi)
        return b;
    return {a.mi, a.cnt + b.cnt};
}

class SegTree {
    vector<Info> arr;
    vector<i64> lazy;
    int s;

    void push(int n, int nb, int ne) {
        if (!lazy[n]) return;

        arr[n].mi += lazy[n];
        if (nb + 1 != ne) {
            lazy[2 * n] += lazy[n];
            lazy[2 * n + 1] += lazy[n];
        }

        lazy[n] = 0;
    }

    void update(int l, int r, i64 d, int n, int nb, int ne) {
        push(n, nb, ne);
        if (ne <= l || nb >= r) return;
        if (l <= nb && ne <= r) {
            lazy[n] = d;
            push(n, nb, ne);
            return;
        }

        update(l, r, d, 2 * n, nb, (nb + ne) / 2);
        update(l, r, d, 2 * n + 1, (nb + ne) / 2, ne);

        arr[n] = merge(arr[2 * n], arr[2 * n + 1]);
    }

    Info query(int l, int r, int n, int nb, int ne) {
        push(n, nb, ne);
        if (ne <= l || nb >= r) return {(i64)1e18, 1};
        if (l <= nb && ne <= r) return arr[n];

        return merge(
            query(l, r, 2 * n, nb, (nb + ne) / 2),
            query(l, r, 2 * n + 1, (nb + ne) / 2, ne));
    }

public:

    void update(int l, int r, i64 d) { update(l, r, d, 1, 0, s); }
    int query(int l, int r) { return query(l, r, 1, 0, s).cnt; }

    SegTree() { }
    SegTree(int N) {
        s = 1 << (int)ceil(log2(N));
        arr.resize(2 * s, {0, 1});
        lazy.resize(2 * s);

        for (int i = s - 1; i > 0; i--)
            arr[i] = merge(arr[2 * i], arr[2 * i + 1]);
    }
};

#define GOOD_SQUARE_VALUE 1
#define BAD_SQUARE_VALUE 1

int H, W;
vector<vector<int>> grid;
vector<pair<int, int>> pos;

SegTree segtree;

bool get_status(int i, int j, int t) {
    if (i < 0 || j < 0 || i >= H || j >= W)
        return false;
    return grid[i][j] <= t;
}

int get_square_value(int x, int y, int dx, int dy, int t) {
    int cnt = get_status(x, y, t) + get_status(x + dx, y, t)
            + get_status(x, y + dy, t) + get_status(x + dx, y + dy, t);

    switch (cnt) {
    case 1: return GOOD_SQUARE_VALUE;
    case 3: return BAD_SQUARE_VALUE;
    default: return 0;
    }
}

void do_update(int idx, bool rev = false) {
    auto [x, y] = pos[idx];

    int factor = rev ? -1 : +1;
    i64 upd = 0;

    // Remove old squares
    for (auto dx: {-1, +1})
        for (auto dy: {-1, +1})
            upd -= get_square_value(x, y, dx, dy, idx - 1) * factor;

    // Add new squares
    for (auto dx: {-1, +1})
        for (auto dy: {-1, +1})
            upd += get_square_value(x, y, dx, dy, idx) * factor;

    // Push to segment
    segtree.update(idx, H * W, upd);
}

void give_initial_chart(int H, int W, vector<int> R, vector<int> C) {
    ::H = H, ::W = W;
    grid.assign(H, vector<int>(W));
    pos.resize(H * W);

    for (int i = 0; i < H * W; i++) {
        pos[i] = {R[i], C[i]};
        grid[R[i]][C[i]] = i;
    }

    segtree = SegTree(H * W);

    for (int i = 0; i < H * W; i++) {
        do_update(i);
    }
}

int swap_seats(int a, int b) {
    vector<pair<int, int>> to_update;

    for (auto c: {a, b})
        for (int x = max(0, pos[c].first - 1); x <= min(H - 1, pos[c].first + 1); x++)
            for (int y = max(0, pos[c].second - 1); y <= min(W - 1, pos[c].second + 1); y++)
                to_update.emplace_back(x, y);

    sort(to_update.begin(), to_update.end());
    to_update.resize(unique(to_update.begin(), to_update.end()) - to_update.begin());

    for (auto [x, y]: to_update)
        do_update(grid[x][y], true);

    swap(pos[a], pos[b]);
    grid[pos[a].first][pos[a].second] = a;
    grid[pos[b].first][pos[b].second] = b;

    for (auto [x, y]: to_update)
        do_update(grid[x][y]);

    return segtree.query(0, H * W);
}

• Subtask 1: 5 / 5
• Subtask 2: 6 / 6
• Subtask 3: 20 / 20
• Subtask 4: 6 / 6
• Subtask 5: 33 / 33
• Subtask 6: 30 / 30