Submission #584514

#	Time	Username	Problem	Language	Result	Execution time	Memory
584514		acm	K-th path (IZhO11_kthpath)	C++14	100 / 100	9 ms	368 KiB

kthpath

#ifdef ONLINE_JUDGE
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,O3")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#endif
#include <bits/stdc++.h>
#define speed                   \
  ios_base::sync_with_stdio(0); \
  cin.tie(0);                   \
  cout.tie(0);
#define precision     \
  cout.precision(30); \
  cerr.precision(10);
#define ll long long
#define ld long double
#define pb(x) push_back(x)
#define sz(x) (int)x.size()
#define mp(x, y) make_pair(x, y)
#define all(x) x.begin(), x.end()
#define pc(x) __builtin_popcount(x)
#define pcll(x) __builtin_popcountll(x)
#define F first
#define S second
using namespace std;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
void ioi(string name) {
  freopen((name + ".in").c_str(), "r", stdin);
  freopen((name + ".out").c_str(), "w", stdout);
}
ll n, m, k, a[35][35], b[65], dp[35][35], pd[35][35];
ll ok() {
  for (int i = 1; i <= n; i++)
    for (int j = 1; j <= m; j++) dp[i][j] = pd[i][j] = 0;
  pd[n][m] = 1;
  for (int i = n; i >= 1; i--) {
    for (int j = m; j >= 1; j--) {
      if (1 <= i - 1) pd[i - 1][j] += pd[i][j];
      if (1 <= j - 1) pd[i][j - 1] += pd[i][j];
    }
  }
  dp[1][1] = (a[1][1] == b[1]);
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) {
      if (i + 1 <= n && b[i + j] == a[i + 1][j]) dp[i + 1][j] += dp[i][j];
      if (j + 1 <= m && b[i + j] == a[i][j + 1]) dp[i][j + 1] += dp[i][j];
    }
  }
  ll res = dp[n][m];
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) {
      if (i + 1 <= n && b[i + j] > a[i + 1][j]) res += dp[i][j] * pd[i + 1][j];
      if (j + 1 <= m && b[i + j] > a[i][j + 1]) res += dp[i][j] * pd[i][j + 1];
    }
  }
  return res;
}
int main() {
  speed;
  precision;
  // code
  cin >> n >> m;
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) {
      char x;
      cin >> x;
      a[i][j] = x - 'a';
    }
  }
  cin >> k;
  for (int i = 1; i <= n + m - 1; i++) b[i] = 25;
  for (int i = 1; i <= n + m - 1; i++) {
    b[i] = 0;
    while (ok() < k) b[i]++;
    cout << char('a' + b[i]);
  }
  // endl
#ifndef ONLINE_JUDGE
  cerr << "\nTime elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
#endif
  return 0;
}

Compilation message (stderr)

kthpath.cpp: In function 'void ioi(std::string)':
kthpath.cpp:26:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   26 |   freopen((name + ".in").c_str(), "r", stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kthpath.cpp:27:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |   freopen((name + ".out").c_str(), "w", stdout);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 100 / 100