Submission #661301

#	Time	Username	Problem	Language	Result	Execution time	Memory
661301		chanhchuong123	Mecho (IOI09_mecho)	C++17	89 / 100	187 ms	6236 KiB

mecho

#include <bits/stdc++.h>
using namespace std;
#define task "C"
#define fi first
#define se second
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()

template <typename T1, typename T2> bool mini(T1 &a, T2 b) {
  if (a > b) {a = b; return true;} return false;
}
template <typename T1, typename T2> bool maxi(T1 &a, T2 b) {
  if (a < b) {a = b; return true;} return false;
}

const int dx[] = {-1, 0, 0, +1};
const int dy[] = {0, -1, +1, 0};
const int N = 800;
int n, S;
char a[N][N];
int bee[N][N];
int bear[N][N];
pair<int, int> st, en;

int ADD;
bool canMove(int dist, int i, int j) {
  if (bee[i][j] == -1) return true;
  return dist / S < bee[i][j] - ADD;
}

bool check() {
  memset(bear, -1, sizeof(bear));
  queue<pair<int, int>> q;
  bear[st.fi][st.se] = 0;
  q.push(st);
  while (q.size()) {
    int u = q.front().fi;
    int v = q.front().se;
    q.pop();
    for (int i = 0; i < 4; i++) {
      int x = u + dx[i], y = v + dy[i];
      if (x < 0 || x >= n) continue;
      if (y < 0 || y >= n) continue;
      if (a[x][y] == 'T' || a[x][y] == 'H') continue;
      if (bear[x][y] == -1 && canMove(bear[u][v] + 1, x, y)) {
        bear[x][y] = bear[u][v] + 1; q.push(make_pair(x, y));
      }
    }
  }
  int u = en.fi, v = en.se;
  for (int i = 0; i < 4; i++) {
    int x = u + dx[i], y = v + dy[i];
    if (x < 0 || x >= n) continue;
    if (y < 0 || y >= n) continue;
    if (bear[x][y] == -1) continue;
    if (a[x][y] == 'T' || a[x][y] == 'H') continue;
    if (canMove(bear[x][y], x, y)) return true;
  }
  return false;
}

main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0); cout.tie(0);

  if (fopen(task".inp","r")) {
    freopen(task".inp","r",stdin);
    freopen(task".out","w",stdout);
  }

  cin >> n >> S;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      cin >> a[i][j];
      if (a[i][j] == 'M') st = make_pair(i, j);
      if (a[i][j] == 'D') en = make_pair(i, j);
    }
  }
  memset(bee, -1, sizeof(bee));
  queue<pair<int, int>> q;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      if (a[i][j] == 'H') {
        bee[i][j] = 0;
        q.push(make_pair(i, j));
      }
    }
  }
  while (q.size()) {
    int u = q.front().fi;
    int v = q.front().se;
    q.pop();
    for (int i = 0; i < 4; i++) {
      int x = u + dx[i], y = v + dy[i];
      if (x < 0 || x >= n) continue;
      if (y < 0 || y >= n) continue;
      if (a[x][y] == 'T' || a[x][y] == 'D') continue;
      if (bee[x][y] == -1) {
        q.push(make_pair(x, y));
        bee[x][y] = bee[u][v] + 1;
      }
    }
  }
  ADD = 0;
  if (check() == false) {
    cout << "-1";
    return 0;
  }
  int l = 0, r = n * n + n;
  while (r - l > 1) {
    ADD = l + r >> 1;
    if (check()) l = ADD;
    else r = ADD;
  }
  cout << l;
}

Compilation message (stderr)

mecho.cpp:62:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   62 | main() {
      | ^~~~
mecho.cpp: In function 'int main()':
mecho.cpp:111:13: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  111 |     ADD = l + r >> 1;
      |           ~~^~~
mecho.cpp:67:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   67 |     freopen(task".inp","r",stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
mecho.cpp:68:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   68 |     freopen(task".out","w",stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 89 / 100