Submission #467764

#	Time	Username	Problem	Language	Result	Execution time	Memory
467764		Yuisuyuno	Tracks in the Snow (BOI13_tracks)	C++14	100 / 100	939 ms	234348 KiB

tracks

//Nguyen Huu Hoang Minh
#include <bits/stdc++.h>
#define sz(x) int(x.size())
#define all(x) x.begin(),x.end()
#define reset(x) memset(x, 0,sizeof(x))
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define N 4005
#define remain(x) if (x > MOD) x -= MOD
#define ii pair<int, int>
#define iiii pair< ii , ii >
#define viiii vector< iiii >
#define vi vector<int>
#define vii vector< ii >
#define bit(x, i) (((x) >> (i)) & 1)
#define Task "test"
#define int long long

using namespace std;

typedef long double ld;
const int inf = 1e10;
const int minf = -1e10;

char a[N][N];
int n, m;

void readfile()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    if (fopen(Task".inp","r"))
    {
        freopen(Task".inp","r",stdin);
        //freopen(Task".out","w",stdout);
    }
    cin >> n >> m;
    for(int i=1; i<=n; i++){
        for(int j=1; j<=m; j++){
            cin >> a[i][j];
        }
    }
}

int d[N][N];
int dx[4] = {1,-1,0,0};
int dy[4] = {0,0,1,-1};

bool ok(int x, int y){
    if (x < 1 || x > n || y < 1 || y > m) return false;
    return true;
}

void proc()
{
    deque<ii> q;
    d[1][1] = 1;
    int ans = 1;
    q.push_front(ii(1,1));
    while (q.size()){
        int u = q.front().fi;
        int v = q.front().se;
        q.pop_front();
        for(int i=0; i<4; i++){
            int nu = u + dx[i];
            int nv = v + dy[i];
            if (ok(nu,nv) && a[nu][nv]!='.' && d[nu][nv]==0){
                if (a[nu][nv]!=a[u][v]){
                    d[nu][nv] = d[u][v]+1;
                    q.pb(ii(nu,nv));
                    ans = max(ans,d[nu][nv]);
                }
                else{
                    q.push_front(ii(nu,nv));
                    d[nu][nv] = d[u][v];
                    ans = max(ans,d[nu][nv]);
                }
            }
        }
    }
    cout << ans;
}

signed main()
{
    readfile();
    proc();
    return 0;
}

Compilation message (stderr)

tracks.cpp: In function 'void readfile()':
tracks.cpp:36:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   36 |         freopen(Task".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

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