Submission #1255337

#	Time	Username	Problem	Language	Result	Execution time	Memory
1255337		MisterReaper	Tracks in the Snow (BOI13_tracks)	C++20	0 / 100	1276 ms	1114112 KiB

tracks

// File U.cpp created on 09.08.2025 at 00:46:23
#include <bits/stdc++.h>

using i64 = long long;

#ifdef DEBUG 
    #include "/home/ahmetalp/Desktop/Workplace/debug.h"
#else
    #define debug(...) void(23)
#endif

constexpr int max_N = int(4000) + 5;

int N, M;
char A[max_N][max_N];
bool vis1[max_N][max_N];
bool vis2[max_N][max_N];

constexpr int dx[] = {0, +1, 0, -1};
constexpr int dy[] = {+1, 0, -1, 0};

std::vector<std::pair<int, int>> pnts;
void dfs1(int x, int y) {
    vis1[x][y] = true;
    pnts.emplace_back(x, y);
    for (int d = 0; d < 4; ++d) {
        int nx = x + dx[d], ny = y + dy[d];
        if (0 <= nx && nx < N && 0 <= ny && ny < M && A[nx][ny] != '.' && vis1[nx][ny] == false) {
            dfs1(nx, ny);
        }
    }
}

void dfs2(int x, int y) {
    vis2[x][y] = true;
    for (int d = 0; d < 4; ++d) {
        int nx = x + dx[d], ny = y + dy[d];
        if (0 <= nx && nx < N && 0 <= ny && ny < M && A[nx][ny] == A[x][y] && vis2[nx][ny] == false) {
            dfs2(nx, ny);
        }
    }
}

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

    std::cin >> N >> M;
    for (int i = 0; i < N; ++i) {
        for (int j = 0; j < M; ++j) {
            std::cin >> A[i][j];
        }
    }

    int ans = 0;

    for (int i = 0; i < N; ++i) {
        for (int j = 0; j < M; ++j) {
            if (A[i][j] == '.' || vis1[i][j]) {
                continue;
            }
            dfs1(i, j);
            int cnt[2] {};
            for (auto[x, y] : pnts) {
                if (vis2[x][y]) {
                    continue;
                }
                dfs2(x, y);
                cnt[A[x][y] == 'F'] += 1;
            }
            ans += std::min(cnt[0], cnt[1]) + 1;
            pnts.clear();
        }
    }

    std::cout << ans << '\n';

    return 0;
}

• Subtask 1: 0 / 30
• Subtask 2: 0 / 70