Submission #927184

#	Time	Username	Problem	Language	Result	Execution time	Memory
927184		haru09	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	538 ms	132520 KiB

tracks

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define fi first
#define se second
#define task "code"

const int ar=4e3+5;
const ll mod=1e9+7;
int m,n;
int a[ar][ar];
int dx[]={1,-1,0,0};
int dy[]={0,0,1,-1};
deque<pair<int,int>> qu;
bool vs[ar][ar];
int ans=0;
void bfs()
{
    qu.push_back({1,1});
    vs[1][1]=true;
    int last=0;
    while(qu.size())
    {
        pair<int,int> p=qu.front();
        qu.pop_front();
        int u=p.fi;
        int v=p.se;
        if (a[u][v]!=last) ans++;
        last=a[u][v];
        for (int i=0;i<=3;i++)
        {
            int x=u+dx[i];
            int y=v+dy[i];
            if (x<1 || x>m || y<1 || y>n) continue;
            if (a[x][y]==0) continue;
            if (vs[x][y]) continue;
            if (a[x][y]==a[u][v])
            {
                qu.push_front({x,y});
            }
            else qu.push_back({x,y});
            vs[x][y]=true;
        }
    }
    cout<<ans;
}
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
    if (fopen(task".inp","r"))
    {
        freopen(task".inp","r",stdin);
        freopen(task".out","w",stdout);
    }
    cin>>m>>n;
    for (int i=1;i<=m;i++)
    {
        for (int j=1;j<=n;j++)
        {
            char x;
            cin>>x;
            if (x=='.') a[i][j]=0;
            else if (x=='R') a[i][j]=1;
            else a[i][j]=2;
        }
    }
    bfs();
}

Compilation message (stderr)

tracks.cpp: In function 'int main()':
tracks.cpp:53:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   53 |         freopen(task".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
tracks.cpp:54:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   54 |         freopen(task".out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

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