Submission #821724

#	Time	Username	Problem	Language	Result	Execution time	Memory
821724		Metal_Sonic	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	699 ms	137424 KiB

tracks

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define sz(x) (x).size()
#define all(x) x.begin() , x.end()
#define F first
#define S second
void Sonic(string name = "") {
    ios_base::sync_with_stdio(false); cin.tie(nullptr);
    if(sz(name)){
        freopen((name+".in").c_str(), "r", stdin);
        freopen((name+".out").c_str(), "w", stdout);
    }
}
int xd[] = {0, 1, -1, 0, 1, 1, -1, -1};
int yd[] = {1, 0, 0, -1, 1, -1, 1, -1};
const int mod = 1e9 + 7, MAXN = 1e6 + 5;

void run_test_case(){
    int n,m;cin>>n>>m;
    char grid[n][m];
    for(int i = 0; i < n; i++){
        for(int j = 0; j < m; j++)cin>>grid[i][j];
    }
    vector<vector<int>>dist(n,vector<int>(m,INT_MAX));
    deque<pair<int,int>>dq;
    dist[0][0] = 1;
    dq.push_back({0,0});
    while(!dq.empty()){
        int i = dq.front().first, j = dq.front().second;
        dq.pop_front();
        for(int k = 0; k < 4; k++){
            int ni = i+xd[k], nj = j+yd[k];
            if(ni<0||nj<0||ni>=n||nj>=m||grid[ni][nj]=='.')continue;
            bool f = (grid[i][j] == grid[ni][nj]);
            if(dist[i][j] + !f < dist[ni][nj]){
                if(!f)dq.push_back({ni,nj});
                else dq.push_front({ni,nj});
                dist[ni][nj] = dist[i][j]+!f;
            }
        }
    }
    int ans = 0;
    for(int i = 0; i < n; i++){
        for(int j = 0; j < m; j++){
            if(dist[i][j]==INT_MAX)continue;
            ans = max(ans,dist[i][j]);
        }
    }
    cout<<ans;
}
int main(){
    Sonic();
    int T = 1;
    //cin>>T;
    while(T--){
        run_test_case();
    }
    return 0;
}

Compilation message (stderr)

tracks.cpp: In function 'void Sonic(std::string)':
tracks.cpp:11:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   11 |         freopen((name+".in").c_str(), "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
tracks.cpp:12:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   12 |         freopen((name+".out").c_str(), "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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