Submission #1272309

#	Time	Username	Problem	Language	Result	Execution time	Memory
1272309		squatrian	Tracks in the Snow (BOI13_tracks)	C++20	100 / 100	635 ms	209040 KiB

tracks

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
using std::mt19937_64;
using std::random_device;
using std::uniform_int_distribution;
#include <numeric>
#define ff              first
#define ss              second
#define int              long long
#define pb              push_back
#define mp              make_pair
#define pii             pair<int,int>
#define vi              vector<int>
#define mii             map<int,int>
#define pqb             priority_queue<int>
#define pqs             priority_queue<int,vi,greater<int> >
#define setbits(x)      __builtin_popcountll(x)
#define zrobits(x)      __builtin_ctzll(x)
#define mod             998244353
#define inf             1e18
#define ps(x,y)         fixed<<setprecision(y)<<x
#define mk(arr,n,type)  type *arr=new type[n];
mt19937                 rng(chrono::steady_clock::now().time_since_epoch().count());
 
typedef tree<pair<int,int>, null_type, less<pair<int,int>>, rb_tree_tag, tree_order_statistics_node_update> pbds;

 
void cpc()
{
#ifndef ONLINE_JUDGE
    freopen("shuffle.in", "r", stdin);
    freopen("shuffle.out", "w", stdout);
#endif
}
int dx[] = {-1, 0, 1, 0};
int dy[] = {0, 1, 0, -1};
int exp(int x, int n, int m) {
    if(x == 0 and n == 0) return 1;
    x %= m; 
    int res = 1;
    while (n > 0) {
        if (n % 2 == 1) { res = res * x % m; }
        x = x * x % m;
        n /= 2;
    }
    return res;
}
int gcd(int a,int b){
    if(a == 0) return b;
    return gcd(b%a,a);
}
bool check(int x,int y,int n,int m){
    if(x < 0 or y < 0 or x >= n or y >= m) return false;
    return true;
}
bool valid(int &x,int &m){
    int prev = x&1;
    for(int i = 1 ; i < m; i++){
       if((x&(1<<i)) == 0 and prev == 0) return false;
       prev = (x&(1<<i));
    }
    return true;
}
signed main()
{  
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    // cpc();
    int t=1;
    // cin >> t;
    while(t--){
     int n,m;
     cin >> n >> m;
     vector<vector<char>> v(n,vector<char>(m));
     for(int i = 0 ; i < n; i++){
        for(int j = 0 ; j < m; j++){
            cin >> v[i][j];
        }
     }
     deque<pair<int,int>> dq;
     dq.push_back({0,0});
     vector<vector<int>> visited(n,vector<int>(m,0));
     visited[0][0] = 1;
     int ans = 1;
     while(!dq.empty()){
       int i = dq.front().ff;
       int j = dq.front().ss;
       ans = max(ans,visited[i][j]);
       dq.pop_front();
       for(int ind = 0 ; ind < 4; ind++){
         int x = i+dx[ind];
         int y = j+dy[ind];
         if(check(x,y,n,m) and visited[x][y]==0 and v[x][y] != '.'){
             if(v[i][j] == v[x][y]){
                dq.push_front({x,y});
                visited[x][y] = visited[i][j];
             }
             else{
               dq.push_back({x,y});
               visited[x][y] = visited[i][j]+1;
             }
         }
       }
     }
     cout<<ans<<endl;
     
   }
    return 0;
}

Compilation message (stderr)

tracks.cpp: In function 'void cpc()':
tracks.cpp:34:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   34 |     freopen("shuffle.in", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
tracks.cpp:35:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   35 |     freopen("shuffle.out", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~

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