Submission #1081280

#	Time	Username	Problem	Language	Result	Execution time	Memory
1081280		MrPavlito	Tracks in the Snow (BOI13_tracks)	C++17	56.25 / 100	378 ms	451736 KiB

tracks

#include <bits/stdc++.h>
#define int long long
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define sc second
#define endl "\n"
#define pii pair<int,int>

using namespace std;

const int MAXN = 2e6;
const int mod7 = 1e9+7;
const long long inf = 1e18;
vector<vector<pii>> graf(MAXN);
vector<bool> visited(MAXN);
char val[MAXN];
vector<int> dist(MAXN,inf);

set<pii> pq;

/*
void dfs(int nod)
{
    visited[nod] = 1;
    pq.insert(mp(0, nod));
    dist[nod] = 0;
    for(auto x: graf[nod])if(val[nod] == val[x.fi] && !visited[x.fi])dfs(x.fi);
}
*/

void dikstra()
{
    dist[0] = 0;
    pq.insert({0,0});
    while(!pq.empty())
    {
        auto it = pq.begin();
        int u = it -> sc;
        pq.erase(it);
        for(auto x: graf[u])
        {
            int nod = x.fi;
            int w = x.sc;
            if(dist[nod] > dist[u]+w)
            {
                pq.erase({dist[nod], nod});
                dist[nod] = dist[u]+w;
                pq.insert({dist[nod], nod});
            }
        }
    }
}

signed main()
{
    ios_base::sync_with_stdio(false),cin.tie(0), cout.tie(0);
    int tt=1;
    //cin >> tt;
    while(tt--)
    {
        int n,m;
        cin >> n >> m;
        for(int i=0; i<n; i++)
        {
            string s;cin >> s;
            for(int j=0; j<m; j++)
            {

                val[i*m+j] = s[j];
                if(s[j] == '.')continue;
                if(i>0 && val[(i-1)*m+j] != '.')
                {
                    graf[i*m+j].pb(mp((i-1)*m+j,val[i*m+j] != val[(i-1)*m+j]));
                    graf[(i-1)*m+j].pb(mp(i*m+j,val[i*m+j] != val[(i-1)*m+j]));
                }
                if(j>0 && val[i*m+j-1] != '.')
                {
                    graf[i*m+j].pb(mp(i*m+j-1,val[i*m+j] != val[i*m+j-1]));
                    graf[i*m+j-1].pb(mp(i*m+j,val[i*m+j] != val[i*m+j-1]));
                }
            }
        }
        //dfs(0);
        dikstra();
        int mx = 0;
        for(auto x: dist)if(x!=inf)mx = max(mx,x);
        cout << mx+1 << endl;
    }
}

• Subtask 1: 30 / 30
• Subtask 2: 26.25 / 70