Submission #383720

#	Time	Username	Problem	Language	Result	Execution time	Memory
383720		Valera_Grinenko	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	785 ms	131132 KiB

tracks

#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimization ("unroll-loops")
#include <iostream>
#include <fstream>
#include <algorithm>
#include <vector>
#include <set>
#include <stack>
#include <map>
#include <unordered_map>
#include <iomanip>
#include <cmath>
#include <queue>
#include <bitset>
#include <numeric>
#include <array>
#include <cstring>
#include <random>
#include <chrono>
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define make_unique(x) sort(all((x))); (x).resize(unique(all((x))) - (x).begin())
typedef long long ll;
typedef long double ld;
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
// template<class T>
// using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
const int N = 4000;
char s[N][N];
int d[N][N];
int main() {

  ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);

  int h, w;

  cin >> h >> w;

  for(int i = 0; i < h; i++)
    for(int j = 0; j < w; j++)
      cin >> s[i][j];

  deque<pair<int, int> > q;

  q.push_front(mp(0, 0));

  d[0][0] = 1;

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

  int ans = 1;

  while(!q.empty()) {
    auto cv = q.front(); q.pop_front();
    int x = cv.fi, y = cv.se;
    ans = max(ans, d[x][y]);
    for(int mv = 0; mv < 4; mv++) {
      int cx = x + dx[mv], cy = y + dy[mv];
      if(cx >= 0 && cx < h && cy >= 0 && cy < w && d[cx][cy] == 0 && s[cx][cy] != '.') {
        d[cx][cy] = d[x][y] + (s[cx][cy] != s[x][y]);
        if(d[cx][cy] > d[x][y]) q.push_back(mp(cx, cy));
        else q.push_front(mp(cx, cy));
      }
    }
  }

  cout << ans;

  return 0;
}
/*

*/

Compilation message (stderr)

tracks.cpp:3: warning: ignoring #pragma GCC optimization [-Wunknown-pragmas]
    3 | #pragma GCC optimization ("unroll-loops")
      |

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