Submission #916661

#	Time	Username	Problem	Language	Result	Execution time	Memory
916661		May27_th	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	660 ms	122464 KiB

tracks

#include <bits/stdc++.h>
#define int64_t long long
#define double long double
using namespace std;
using type = int64_t;
const long long mod = 1000000007, inf = 1e18;
const int base = 33;
const int N = 2e5 + 10;
const int LG = 20;

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

void Minimize(int64_t &a, int64_t b) {if(b < a) a = b;}
void Maximize(int &a, int b) {if(b > a) a = b;}
void Add(int64_t& a, int64_t b) {a = a + b; a %= mod;}
void Dec(int64_t& a, int64_t b) {a = a - b + mod; a %= mod;}

int h, w; char g[4010][4010]; int d[4005][4005];
void Solve(void)
{
    cin >> h >> w;
    for(int i = 1; i <= h; i ++){
        for(int j = 1; j <= w; j ++){
            cin >> g[i][j];
            d[i][j] = 1e9;
        }
    }
    deque<pair<int, int>>q;
    d[1][1] = 1;
    q.push_front(make_pair(1, 1));
    while(!q.empty()){
        int u = q.front().first;
        int v = q.front().second;
        q.pop_front();
        for(int i = 0; i < 4; i ++){
            int nu = u + dx[i];
            int nv = v + dy[i];
            if(nu >= 1 && nv >= 1 && nu <= h && nv <= w){
                int weight = (g[u][v] != g[nu][nv]);
                if(g[nu][nv] == '.') continue;
                if(d[nu][nv] > d[u][v] + weight){
                    d[nu][nv] = d[u][v] + weight;
                    //cout << d[nu][nv] << "\n";
                    if(weight == 1) q.push_back(make_pair(nu, nv));
                    else q.push_front(make_pair(nu, nv));
                }
            }
        }
    }
    int ans = 0;
    for(int i = 1; i <= h; i ++){
        for(int j = 1; j <= w; j ++){
            //cout << d[i][j] << " ";
            if(g[i][j] != '.')
                ans = max(ans, d[i][j]);
        }
        //cout << "\n";
    }
    cout << ans;
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    if(fopen("poetry.in", "r")){
        freopen("poetry.in", "r", stdin);
        freopen("poetry.out", "w", stdout);
    }
    if(fopen("A.inp", "r")){
        freopen("A.inp", "r", stdin);
        freopen("A.out", "w", stdout);
    }
    int tc = 1;
    //cin >> tc;
    while(tc --){
        Solve();
    }
}

Compilation message (stderr)

tracks.cpp: In function 'int main()':
tracks.cpp:68:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   68 |         freopen("poetry.in", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
tracks.cpp:69:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   69 |         freopen("poetry.out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
tracks.cpp:72:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   72 |         freopen("A.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
tracks.cpp:73:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   73 |         freopen("A.out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

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