Submission #733334

#	Time	Username	Problem	Language	Result	Execution time	Memory
733334		n0sk1ll	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	641 ms	174276 KiB

tracks

#include <bits/stdc++.h>
 
#define FAST ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);cerr.tie(0)
#define mp make_pair
#define xx first
#define yy second
#define pb push_back
#define pf push_front
#define popb pop_back
#define popf pop_front
#define all(x) x.begin(),x.end()
#define ff(i,a,b) for (int i = a; i < b; i++)
#define fff(i,a,b) for (int i = a; i <= b; i++)
#define bff(i,a,b) for (int i = b-1; i >= a; i--)
#define bfff(i,a,b) for (int i = b; i >= a; i--)
 
using namespace std;
long double typedef ld;
unsigned int typedef ui;
long long int typedef li;
pair<int,int> typedef pii;
pair<li,li> typedef pli;
pair<ld,ld> typedef pld;
vector<vector<int>> typedef graph;
unsigned long long int typedef ull;
//const int mod = 998244353;
const int mod = 1000000007;
 
 
 
 
 
 
 
//Note to self: Check for overflow
 
int n,m;
char tab[4004][4004];
 
bool valid(int x, int y)
{
    if (x<0 || y<0) return false;
    if (x>=n || y>=m) return false;
    if (tab[x][y]=='.') return false;
    return true;
}
 
int main()
{
    FAST;
 
    cin>>n>>m;
    ff(i,0,n) cin>>tab[i];
 
    if (tab[0][0]=='.') return cout<<0,0;
 
    int maxd=-1;
    deque<pair<int,pii>> bfs;
    bfs.pb({1,{0,0}});
 
    while (!bfs.empty())
    {
        int d=bfs.front().xx;
        int x=bfs.front().yy.xx;
        int y=bfs.front().yy.yy;
        bfs.popf();
 
        if (tab[x][y]=='.') continue;
 
        if (valid(x-1,y))
        {
            if (tab[x-1][y]!=tab[x][y]) bfs.pb({d+1,{x-1,y}});
            else bfs.pf({d,{x-1,y}});
        }
        if (valid(x+1,y))
        {
            if (tab[x+1][y]!=tab[x][y]) bfs.pb({d+1,{x+1,y}});
            else bfs.pf({d,{x+1,y}});
        }
        if (valid(x,y-1))
        {
            if (tab[x][y-1]!=tab[x][y]) bfs.pb({d+1,{x,y-1}});
            else bfs.pf({d,{x,y-1}});
        }
        if (valid(x,y+1))
        {
            if (tab[x][y+1]!=tab[x][y]) bfs.pb({d+1,{x,y+1}});
            else bfs.pf({d,{x,y+1}});
        }
 
        tab[x][y]='.';
        maxd=max(maxd,d);
    }
 
    cout<<maxd<<"\n";
}
 
//Note to self: Check for overflow

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