Submission #1095215

#	Time	Username	Problem	Language	Result	Execution time	Memory
1095215		InvMOD	Tracks in the Snow (BOI13_tracks)	C++14	100 / 100	906 ms	152268 KiB

tracks

#include<bits/stdc++.h>

using namespace std;

const int dx[4] = {1, -1, 0, 0};
const int dy[4] = {0, 0, -1, 1};

void solve()
{
    int n,m; cin >> n >> m;
    vector<vector<int>> a(n, vector<int>(m));

    for(int i = 0; i < n; i++){
        for(int j = 0; j < m; j++){
            char c; cin >> c;
            a[i][j] = (c != '.' ? (c == 'F' ? 1 : 2) : 0);
        }
    }

    vector<vector<int>> mx_dif(n, vector<int>(m));

    function<bool(int,int)> init = [&](int x, int y){
        return x >= 0 && x < n && y >= 0 && y < m && a[x][y] != 0 && !mx_dif[x][y];
    };

    function<int(int,int)> id = [&](int x, int y){
        return x*m + y;
    };

    deque<int> dq;
    dq.push_back(0);
    mx_dif[0][0] = 1;

    while(!dq.empty()){
        int cur_id = dq.front(); dq.pop_front();

        int y = cur_id % m;
        int x = (cur_id - y) / m;
        for(int i = 0; i < 4; i++){
            int xx = dx[i] + x;
            int yy = dy[i] + y;
            if(init(xx, yy) && !mx_dif[xx][yy]){
                if(a[xx][yy] != a[x][y]){
                    mx_dif[xx][yy] = mx_dif[x][y] + 1;
                    dq.push_back(id(xx, yy));
                }
                else{
                    mx_dif[xx][yy] = mx_dif[x][y];
                    dq.push_front(id(xx, yy));
                }
            }
        }
    }

    int answer = 0;
    for(int i = 0; i < n; i++){
        for(int j = 0; j < m; j++){
            answer = max(answer, mx_dif[i][j]);
        }
    }
    cout << answer <<"\n";
}

int32_t main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    #define name "InvMOD"
    if(fopen(name".INP", "r")){
        freopen(name".INP", "r", stdin);
        freopen(name".OUT", "w", stdout);
    }

    solve();
    return 0;
}

Compilation message (stderr)

tracks.cpp: In function 'int32_t main()':
tracks.cpp:70:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   70 |         freopen(name".INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
tracks.cpp:71:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   71 |         freopen(name".OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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