Submission #1280837

#	Time	Username	Problem	Language	Result	Execution time	Memory
1280837		cjspd_oly	Collecting Mushrooms (NOI18_collectmushrooms)	C++17	100 / 100	12 ms	14392 KiB

mushrooms

#include <bits/stdc++.h>

using namespace std;

using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;

using pii = pair<int, int>;
using vii = vector<pii>;
using vvii = vector<vii>;

using l = long long;
using vl = vector<l>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;

using pll = pair<l, l>;
using vll = vector<pll>;
using vvll = vector<vll>;

using d = double;
using vd = vector<d>;
using vvd = vector<vd>;
using vvvd = vector<vvd>;

using ld = long double;
using vld = vector<ld>;
using vvld = vector<vld>;
using vvvld = vector<vvld>;

using vb = vector<bool>;
using vvb = vector<vb>;
using pbb = pair<bool, bool>;
using vbb = vector<pbb>;

#define ff first
#define ss second

#define pb push_back
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) (int)(x).size()

void setIO(string name = "")
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    if (!name.empty())
    {
        (void)freopen((name + ".in").c_str(), "r", stdin);
        (void)freopen((name + ".out").c_str(), "w", stdout);
    }
}

const ld pi = 3.14159265358979323846;

const l LINF = 1e18;
const l INF = 1e9;

const l MOD = 1e9 + 7;
// const l MOD = 998244353;

const l MAXN = 2e5 + 5;

void solve()
{
    int R, C, D, K;
    cin >> R >> C >> D >> K;

    vector<string> grid(R);
    for (int i = 0; i < R; i++)
        cin >> grid[i] ;

    vvi diff(R + 1, vi(C + 1, 0));

    // * mark sprinkler coverage with 2d-diff array
    for (int i = 0; i < R; ++i)
    {
        for (int j = 0; j < C; ++j)
        {
            if (grid[i][j] != 'S')
                continue;

            int r1 = max(0, i - D), c1 = max(0, j - D),
                r2 = min(R - 1, i + D), c2 = min(C - 1, j + D);

            ++diff[r1][c1], ++diff[r2 + 1][c2 + 1],
                --diff[r2 + 1][c1], --diff[r1][c2 + 1];
        }
    }

    // * build 2d-prefix sum to get no. of sprinklers per cell
    vvi water(R + 3, vi(C + 3, 0));
    for (int i = 0; i < R; ++i)
    {
        for (int j = 0; j < C; ++j)
        {
            water[i][j] = diff[i][j];
            if (i > 0)
                water[i][j] += water[i - 1][j];
            if (j > 0)
                water[i][j] += water[i][j - 1];
            if (i > 0 && j > 0)
                water[i][j] -= water[i - 1][j - 1];
        }
    }

    int ans = 0;
    for (int i = 0; i < R; ++i)
        for (int j = 0; j < C; ++j)
            if (grid[i][j] == 'M' && water[i][j] >= K)
                ++ans;

    cout << ans << "\n";
}

int main()
{
    setIO("");

#ifndef ONLINE_JUDGE
    // setIO("filename");
#endif

    int t = 1;
    // cin >> t;
    while (t--)
        solve();

    return 0;
}

Compilation message (stderr)

mushrooms.cpp: In function 'void setIO(std::string)':
mushrooms.cpp:52:22: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   52 |         (void)freopen((name + ".in").c_str(), "r", stdin);
      |               ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
mushrooms.cpp:53:22: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   53 |         (void)freopen((name + ".out").c_str(), "w", stdout);
      |               ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 9 / 9
• Subtask 2: 10 / 10
• Subtask 3: 18 / 18
• Subtask 4: 23 / 23
• Subtask 5: 19 / 19
• Subtask 6: 21 / 21