Submission #507349

#	Time	Username	Problem	Language	Result	Execution time	Memory
507349		Falcon	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	774 ms	59608 KiB

tracks

#include <bits/stdc++.h>

#ifdef DEBUG
    #include "debug.hpp"
#endif

using namespace std;

#define all(c)        (c).begin(), (c).end()
#define rall(c)       (c).rbegin(), (c).rend()
#define rep(i, N)     for (int i = 0; i < (N); ++i)
#define rrep(i, N)    for (int i = (N)-1; i >= 0; --i)
#define rep1(i, N)    for (int i = 1; i <= (N); ++i)
#define rep2(i, s, e) for (int i = (s); i <= (e); ++i)

#ifdef DEBUG
    #define debug(x...)                                                        \
        do {                                                                   \
            ++dbg::depth;                                                      \
            string dbg_vals = dbg::to_string(x);                               \
            --dbg::depth;                                                      \
            dbg::fprint(__func__, __LINE__, #x, dbg_vals);                     \
        } while (false)
#else
    #define debug(...) 42
#endif

template<typename T> inline T& ckmin(T& a, T b) { return a = a > b ? b : a; }
template<typename T> inline T& ckmax(T& a, T b) { return a = a < b ? b : a; }

template<typename T, size_t dim> class tensor {
private:
    vector<tensor<T, dim - 1>> v;

public:
    template<typename... V>
    tensor(size_t d, V... ds): v(d, tensor<T, dim - 1>(ds...)) {}

    tensor<T, dim - 1>& operator[](size_t i) { return v[i]; }

    size_t size() { return v.size(); }

    auto begin() { return v.begin(); }

    auto end() { return v.end(); }
};

template<typename T> class tensor<T, 0> {
private:
    T v;

public:
    tensor(T a = T{}): v{a} {}

    operator T() { return v; }
};

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    int H, W;
    cin >> H >> W;
    vector<string> grid(H);
    rep(i, H) cin >> grid[i];

    tensor<bool, 2> vis(H, W);
    int ans{};

    queue<pair<int, int>> a, b;
    b.push({0, 0});
    vis[0][0] = true;

    auto check = [&](int i, int j, char c) -> void {
        if (i < 0 || j < 0 || i >= H || j >= W) return;
        if (grid[i][j] == '.' || vis[i][j]) return;
        vis[i][j] = true;
        if (grid[i][j] == c)
            a.push({i, j});
        else
            b.push({i, j});
    };

    while (!b.empty()) {
        ++ans;
        swap(a, b);
        while (!a.empty()) {
            auto [i, j] = a.front();
            check(i + 1, j, grid[i][j]);
            check(i - 1, j, grid[i][j]);
            check(i, j + 1, grid[i][j]);
            check(i, j - 1, grid[i][j]);
            a.pop();
        }
    }

    cout << ans << '\n';

    return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 70 / 70