Submission #1295308

#	Time	Username	Problem	Language	Result	Execution time	Memory
1295308		ulvix	Tracks in the Snow (BOI13_tracks)	C++20	100 / 100	532 ms	209084 KiB

tracks

#include <bits/stdc++.h>
#ifdef ULVI
    #define db(x)          cerr<<"[ "<<#x<<" = "<<(x)<<" ]\n"
    #define dbv(v)         cerr<<#v<<" = [ ";for(auto &__x : v)cerr<<__x<<' ';cerr<<"]\n"
    #define line()         cerr<<string(80, '-')<<'\n'
#else
    #define db(x)
    #define dbv(v)
    #define line()
#endif
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define ff first
#define ss second
#define enld endl
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef pair<ll,ll> pll;
const ll sz=2e5+100;
const ll mod=1e9+7;
const ll inf=1e18;
template<class T>
using indexed_set=tree<T,null_type,less<T>,rb_tree_tag,tree_order_statistics_node_update>;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll xx[]={1,-1,0,0};
ll yy[]={0,0,1,-1};
void solve(){
    ll n,m;
    cin>>n>>m;
    vector<string> v(n+5);
    for(ll i=1;i<=n;i++){
        cin>>v[i];
        v[i]='&'+v[i];
    }
    vector<vector<ll>> dist(n+5,vector<ll>(m+5,inf));
    dist[1][1]=1;
    deque<pll> dq;
    dq.push_back({1,1});
    while(!dq.empty()){
        auto [x,y]=dq.front();
        dq.pop_front();
        for(ll i=0;i<4;i++){
            ll nx=x+xx[i],ny=y+yy[i];
            if(nx<1 || ny<1 || nx>n || ny>m) continue;
            if(v[nx][ny]=='.') continue;
            ll c=(v[x][y]!=v[nx][ny]);
            if(dist[nx][ny]>dist[x][y]+c){
                dist[nx][ny]=dist[x][y]+c;
                if(c) dq.push_back({nx,ny});
                else dq.push_front({nx,ny});
            }
        }
    }
    ll mx=0;
    for(ll i=1;i<=n;i++){
        for(ll j=1;j<=m;j++){
            if(v[i][j]=='.') continue;
            mx=max(mx,dist[i][j]);
        }
    }
    cout<<mx<<'\n';
}

int main(){
    //freopen("input.txt","r",stdin);
    //freopen("output.txt","w",stdout);
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    ll t=1;
    //cin>>t;
    for(ll _=1;_<=t;_++){
        //cout<<"Scenario #"<<_<<":\n";
        solve();
    }
}

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