Submission #310809

#	Time	Username	Problem	Language	Result	Execution time	Memory
310809		VROOM_VARUN	Tracks in the Snow (BOI13_tracks)	C++14	19.79 / 100	1781 ms	268484 KiB

tracks

/*
ID: varunra2
LANG: C++
TASK: tracks
*/

#include <bits/stdc++.h>
using namespace std;

#ifdef DEBUG
#include "lib/debug.h"
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#define debug_arr(...) \
  cerr << "[" << #__VA_ARGS__ << "]:", debug_arr(__VA_ARGS__)
#pragma GCC diagnostic ignored "-Wsign-compare"
//#pragma GCC diagnostic ignored "-Wunused-parameter"
//#pragma GCC diagnostic ignored "-Wunused-variable"
#else
#define debug(...) 42
#endif

#define EPS 1e-9
#define IN(A, B, C) assert(B <= A && A <= C)
#define INF (int)1e9
#define MEM(a, b) memset(a, (b), sizeof(a))
#define MOD 1000000007
#define MP make_pair
#define PB push_back
#define all(cont) cont.begin(), cont.end()
#define rall(cont) cont.end(), cont.begin()
#define x first
#define y second

const double PI = acos(-1.0);
typedef long long ll;
typedef long double ld;
typedef pair<int, int> PII;
typedef map<int, int> MPII;
typedef multiset<int> MSETI;
typedef set<int> SETI;
typedef set<string> SETS;
typedef vector<int> VI;
typedef vector<PII> VII;
typedef vector<VI> VVI;
typedef vector<string> VS;

#define rep(i, a, b) for (int i = a; i < (b); ++i)
#define trav(a, x) for (auto& a : x)
#define sz(x) (int)(x).size()
typedef pair<int, int> pii;
typedef vector<int> vi;
#pragma GCC diagnostic ignored "-Wsign-compare"
// util functions

VVI vals;
int h, w;
vector<vector<bool>> vis;
int get(PII a, PII b) { return vals[a.x][a.y] != vals[b.x][b.y]; }

bool inbnds(PII a) {
  bool x = a.x >= 0 and a.x < h and a.y >= 0 and a.y < w;
  if (x == false) return false;

  return vals[a.x][a.y] != 0 and vis[a.x][a.y] == false;
}

VI dx = {0, -1, 0, 1};
VI dy = {1, 0, -1, 0};

int dij() {
  deque<pair<int, PII>> dq;

  dq.PB(MP(0, MP(0, 0)));
  int ret = 0;
  while (!dq.empty()) {
    auto x = dq.front();
    dq.pop_front();
    ret = max(ret, x.x);
    if (vis[x.y.x][x.y.y]) continue;
    vis[x.y.x][x.y.y] = true;

    for (int i = 0; i < 4; i++) {
      PII nw = MP(x.y.x + dx[i], x.y.y + dy[i]);
      if (inbnds(nw)) {
        int gt = get(x.y, nw);
        if (gt == 1) {
          dq.PB(MP(x.x + gt, nw));
        } else
          dq.push_front(MP(x.x + gt, nw));
      }
    }
  }

  return ret;
}

int main() {
  // #ifndef ONLINE_JUDGE
  // freopen("tracks.in", "r", stdin);
  // freopen("tracks.out", "w", stdout);
  // #endif
  cin.sync_with_stdio(0);
  cin.tie(0);

  cin >> h >> w;

  vals.resize(h);
  vis.resize(h);
  for (int i = 0; i < h; i++) {
    vals[i].assign(w, 0);
    vis[i].assign(w, false);
    for (int j = 0; j < w; j++) {
      char c;
      cin >> c;
      if (c == 'R')
        vals[i][j] = 1;
      else
        vals[i][j] = 2;
    }
  }

  cout << dij() + 1 << '\n';

  return 0;
}

• Subtask 1: 6.666666666666667 / 30
• Subtask 2: 13.125 / 70