Submission #1366734

#TimeUsernameProblemLanguageResultExecution timeMemory
1366734chithanhnguyenFurniture (JOI20_furniture)C++20
100 / 100
172 ms4648 KiB
/*
Author: Nguyen Chi Thanh - High School for the Gifted - VNU.HCM (i2528)
*/
#include <bits/stdc++.h>
using namespace std;

/* START OF TEMPALTE */

// #define int long long
#define ll long long
#define ull unsigned long long
#define ld long double
#define pii pair<int, int>
#define pll pair<ll, ll>
#define fi first
#define se second
#define popcount __builtin_popcountll
#define all(x) (x).begin(), (x).end()
#define BIT(x, i) (((x) >> (i)) & 1)
#define MASK(x) (1ll << (x))
#define SZ(a) ((int32_t)a.size())

#define debug(a, l, r) {for (int _i = (l); _i <= (r); ++_i) cout << (a)[_i] << ' '; cout << '\n';}

template<class X, class Y>
bool minimize(X &x, const Y &y) {
    if (x > y) {
        x = y;
        return true;
    } else return false;
}

template<class X, class Y>
bool maximize(X &x, const Y &y) {
    if (x < y) {
        x = y;
        return true;
    } else return false;
}

/* END OF TEMPALTE */

const int MAXN = 1005;
int dx[] = {1, -1, 0, 0};
int dy[] = {0, 0, 1, -1};
int n, m, q;
bool grid[MAXN][MAXN];
bool canPass[MAXN][MAXN];

bool valid(int r, int c) {
    return (1 <= r && r <= n && 1 <= c && c <= m && grid[r][c] == 0);
}

void init() {
    cin >> n >> m;
    for (int i = 1; i <= n; ++i)
        for (int j = 1; j <= m; ++j)
            cin >> grid[i][j];
}

void computeCanPass() {
    vector<vector<bool>> canReach1(n + 5, vector<bool>(m + 5, 0));

    canReach1[1][1] = 1;
    for (int i = 1; i <= n; ++i)
        for (int j = 1; j <= m; ++j) {
            if (!canReach1[i][j]) continue;
            if (valid(i + 1, j)) canReach1[i + 1][j] = 1;
            if (valid(i, j + 1)) canReach1[i][j + 1] = 1;
        }
    
    vector<vector<bool>> canReach2(n + 5, vector<bool>(m + 5, 0));
    canReach2[n][m] = 1;
    for (int i = n; i >= 1; --i)
        for (int j = m; j >= 1; --j) {
            if (!canReach2[i][j]) continue;
            if (valid(i - 1, j)) canReach2[i - 1][j] = 1;
            if (valid(i, j - 1)) canReach2[i][j - 1] = 1;
        }
    
    for (int i = 1; i <= n; ++i)
        for (int j = 1; j <= m; ++j)
            canPass[i][j] = (canReach1[i][j] && canReach2[i][j]);
    
    // for (int i = 1; i <= n; ++i)
    //     for (int j = 1; j <= m; ++j)
    //         cout << canPass[i][j] << " \n"[j == m];
}

int handleQuery(int r, int c) {
    // Check if the board remain nice
    auto inside = [&] (int r, int c) {
        return (1 <= r && r <= n && 1 <= c && c <= m);
    };

    if (canPass[r][c] == 0) {
        grid[r][c] = 1;
        return 1;
    }

    int diag = r + c; bool ok = 0;
    for (int i = 1; i <= n; ++i) {
        int j = diag - i;

        if (!inside(i, j)) continue;
        if (i == r && j == c) continue;

        if (canPass[i][j] == 1) {
            ok = true;
            break;
        }
    }

    if (!ok) return 0;

    // Update information
    queue<pii> qu;
    qu.push({r, c});
    grid[r][c] = 1;

    // int iter = 1;
    while (SZ(qu)) {
        auto cur = qu.front();
        canPass[cur.fi][cur.se] = 0;
        qu.pop();

        for (int d = 0; d < 4; ++d) {
            int nr = cur.fi + dx[d];
            int nc = cur.se + dy[d];
            if (!inside(nr, nc)) continue;
            if (!canPass[nr][nc]) continue;

            bool isBlocked = 0;

            vector<pii> nxt;
            if (inside(nr + 1, nc)) nxt.push_back({nr + 1, nc});
            if (inside(nr, nc + 1)) nxt.push_back({nr, nc + 1});
            if (SZ(nxt)) {
                bool ok = 1;
                for (auto &e : nxt)
                    if (canPass[e.fi][e.se] == 1) {
                        ok = 0;
                        break;
                    }
                if (ok) isBlocked = 1;
            }

            nxt.clear();
            if (inside(nr - 1, nc)) nxt.push_back({nr - 1, nc});
            if (inside(nr, nc - 1)) nxt.push_back({nr, nc - 1});
            if (SZ(nxt)) {
                bool ok = 1;
                for (auto &e : nxt)
                    if (canPass[e.fi][e.se] == 1) {
                        ok = 0;
                        break;
                    }
                if (ok) isBlocked = 1;
            }

            if (isBlocked) {qu.push({nr, nc});}
        }
    }

    // for (int i = 1; i <= n; ++i)
    //     for (int j = 1; j <= m; ++j)
    //         cout << canPass[i][j] << " \n"[j == m];

    return 1;
}

void solve() {
    computeCanPass();

    int q; cin >> q;
    while (q--) {
        int r, c; cin >> r >> c;
        cout << handleQuery(r, c) << '\n';
    }
}

signed main() {
    #ifdef NCTHANH
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    #endif
    ios_base::sync_with_stdio(0);
    cin.tie(nullptr); cout.tie(nullptr);

    init();
    solve();

    return 0;
}
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