Submission #1120277

#	Time	Username	Problem	Language	Result	Execution time	Memory
1120277		vjudge1	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	1002 ms	458524 KiB

tracks

// Ali
 
// #pragma GCC optimize("Ofast,unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#define int long long int
#define ins insert      
#define pii pair<int,int>
#define pb push_back
#define endl '\n'
#define putr(x) cout<<x<<endl;return; 
#define all(x) x.begin(),x.end()
const int mod = 1e9 +7, sze = 8e6+23, inf = 2e9, LG = 19,pr = 31;
vector<int> graph[sze];
const int dx[4]={-1,0,1,0};
const int dy[4]={0,1,0,-1};
const int asz = 4e3 +5;
int cp[asz][asz];
int n,m;
int used[asz][asz];

int check(int a,int b){
    return (a>=0 && a<n && b>=0 && b<m);
}

void fast(){
    cin>>n>>m;
    vector<vector<char>> arr(n,vector<char>(m)); 
    for(int i=0;i<n;i++){
        for(int j=0;j<m;j++){
            cin>>arr[i][j];
        }
    }
    int ans=1;
    deque<pair<pii,int>> q;
    q.push_front({{0,0},1});
    used[0][0]=1;
    while(!q.empty()){
        pair<pii,int> node = q.front();q.pop_front();
        ans=max(ans,node.second);
        for(int x =0; x<4;x++){
            int a = node.first.first + dx[x];
            int b = node.first.second + dy[x];
            if(check(a,b) && arr[a][b]!='.' && !used[a][b]){
                used[a][b]=1;
                if(arr[a][b] == arr[node.first.first][node.first.second]){
                    q.push_front({{a,b},node.second});
                }
                else{
                    q.push_back({{a,b},node.second +1});
                }
            }
        }

    }
    putr(ans);
}  
/*
5 8
FFR.....
.FRRR...
.FFFFF..
..RRRFFR
.....FFF

1 2
2 1 3

*/
 
signed main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
 
    int tt = 1;
    // cin>>tt;
 
    while(tt--){
        fast();
    }
    return 0;
}

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