Submission #1121239

#	Time	Username	Problem	Language	Result	Execution time	Memory
1121239		Captain_Georgia	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	860 ms	171700 KiB

tracks

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

typedef long long ll;

int32_t main () {

    ios_base::sync_with_stdio(0); 
    cin.tie(0); 
    cout.tie(0); 

    int N, M;
    cin >> N >> M;
    vector<vector<int>> arr(N, vector<int>(M));
    vector<int> X = {0, 0, -1, 1};
    vector<int> Y = {1, -1, 0, 0};
    for (int i = 0;i < N;i ++) {
        for (int j = 0;j < M;j ++) {
            char c;
            cin >> c;
            arr[i][j] = (c == '.' ? -1 : (c == 'R' ? 0 : 1));
        }
    }
    // for (int i = 0;i < N;i ++) {
    //     for (int j = 0;j < M;j ++) {
    //         cout << arr[i][j] << " ";
    //     } cout << "\n";
    // } cout << "\n";

    vector<vector<int>> dist(N, vector<int>(M, 0));
    dist[0][0] = 1;
    deque<array<int, 3>> q;
    q.push_back({0, 0, 1});
    auto check = [&](int x, int y) -> bool {
        if (x >= N || y >= M || x < 0 || y < 0 || arr[x][y] == -1 || dist[x][y] != 0) return 0;
        return 1;
    };
    int ans = 1;
    while (q.size() > 0) {
        auto [sx, sy, cnt] = q.front();
        q.pop_front();
        ans = max(ans, cnt);
        for (int t = 0;t < 4;t ++) {
            int vx = sx + X[t];
            int vy = sy + Y[t];
            if (check (vx, vy)) {
                if (arr[vx][vy] == arr[sx][sy]) {
                    dist[vx][vy] = cnt;
                    q.push_front ({vx, vy, dist[vx][vy]});
                } else {
                    dist[vx][vy] = cnt + 1;
                    q.push_back ({vx, vy, dist[vx][vy]});
                }
            }
        }
    }
    cout << ans << "\n";
    // for (int i = 0;i < N;i ++) {
    //     for (int j = 0;j < M;j ++) {
    //         cout << dist[i][j] << " ";
    //     } cout << "\n";
    // } cout << "\n";
}

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