Submission #770667

#	Time	Username	Problem	Language	Result	Execution time	Memory
770667		ind1v	Tracks in the Snow (BOI13_tracks)	C++11	100 / 100	707 ms	148440 KiB

tracks

#include <bits/stdc++.h>

using namespace std;

const int H = 4005;
const int dI[4] = {-1, 0, +1, 0};
const int dJ[4] = {0, +1, 0, -1};

int h, w;
char d[H][H];
int f[H][H];
bool prc[H][H];

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cin >> h >> w;
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) {
      cin >> d[i][j];
    }
  }
  deque<pair<int, int>> dq;
  memset(f, 0x3f3f3f3f, sizeof(f));
  f[h][w] = 1;
  int mx = 1;
  dq.push_front({h, w});
  while (!dq.empty()) {
    int x, y;
    tie(x, y) = dq.front();
    dq.pop_front();
    if (prc[x][y]) {
      continue;
    }
    mx = max(mx, f[x][y]);
    prc[x][y] = true;
    for (int dir = 0; dir < 4; dir++) {
      int nx = x + dI[dir];
      int ny = y + dJ[dir];
      if (1 <= nx && nx <= h && 1 <= ny && ny <= w) {
        if (d[nx][ny] != '.') {
          if (d[x][y] == d[nx][ny]) {
            if (f[nx][ny] > f[x][y]) {
              f[nx][ny] = f[x][y];
              dq.push_front({nx, ny});
            }
          } else if (f[nx][ny] > f[x][y] + 1) {
            f[nx][ny] = f[x][y] + 1;
            dq.push_back({nx, ny});
          }
        }
      }
    }
  }
  cout << mx;
  return 0;
}

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