Submission #1120895

#	Time	Username	Problem	Language	Result	Execution time	Memory
1120895		Haciyev12	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	1799 ms	311500 KiB

tracks

#include "bits/stdc++.h"
#define fast ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define ll long long
#define pb push_back
#define in insert
#define F first
#define S second
#define vll vector<ll>
#define all(v) v.begin(),v.end()
#define endl '\n'
#define pii pair<ll,ll>
using namespace std;
const ll INF =1e18, mod = 1e9 + 7, N = 3e5 + 5;
ll n,m;
ll a[4005][4005];
ll st;
ll ans = 0;
queue<pii>q;
ll dx[4] = {-1,1, 0, 0};
ll dy[4] = {0, 0, -1, 1};
ll used[4005][4005];
vector<pii>q1;
bool test;
void ch(){
     test = false;
    while(!q.empty()){
        ll x = q.front().F;
        ll y = q.front().S;
        q.pop();
        if(used[x][y] == 1){
            continue;
        }
        used[x][y] = 1;
        for(int i = 0; i < 4; i++){
            ll nx = x + dx[i];
            ll ny = y + dy[i];
            if(nx < 0 || nx >= n || ny < 0 || ny >= m){
                continue;
            }
            if(used[nx][ny] == 0 && st == a[nx][ny]){
                q.push({nx,ny});
            }
            else if(used[nx][ny] == 0 && -st == a[nx][ny]){
                q1.pb({nx,ny});//check again
                test = true;
            }
        }

    }



    if(test){
            ans++;
            for(int i = 0; i < q1.size(); i++){
                q.push({q1[i].F,q1[i].S});
            }
            q1.clear();
            st = -st;//swap
            ch();
    }
}
/*
   x
  y 0 z
    a
*/
void solve(){
    cin >> n >> m;
    char c;
    for(int i = 0; i < n; i++){
        for(int j = 0; j < m; j++){
            cin >> c;
            if(c == 'R'){
                a[i][j] = 1;
            }
            else if(c == 'F'){
                a[i][j] = -1;
            }
        }
    }
    st = a[0][0];
    q.push({0,0});
    ch();
    cout << ans + 1<< endl;
}
int main(){
    fast;
    solve();
    return 0;
}

Compilation message (stderr)

tracks.cpp: In function 'void ch()':
tracks.cpp:55:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   55 |             for(int i = 0; i < q1.size(); i++){
      |                            ~~^~~~~~~~~~~

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