Submission #364849

#	Time	Username	Problem	Language	Result	Execution time	Memory
364849		Sparky_09	K-th path (IZhO11_kthpath)	C++17	100 / 100	2 ms	384 KiB

kthpath

#include "bits/stdc++.h"
using namespace std;
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define trav(a, x) for(auto& a : x)
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<ll, ll> pii;
typedef vector<ll> vi;
typedef vector<pii> vpi;

void usaco(string s){
  freopen((s+".in").c_str(), "r", stdin);
  freopen((s+".out").c_str(), "w", stdout);
}

const int N = 35;
char v[N][N], ans[2*N];
ll dp[N][N];
int n, m, l;

ll dprec(int x, int y){
  int ind = x + y;
  if(ans[ind] != '*' and ans[ind] != v[x][y]){
    return 0;
  }
  if(x == n-1 and y == m-1){
    return 1;
  }
  if(~dp[x][y]){
    return dp[x][y];
  }
  dp[x][y] = 0;
  if(x + 1 < n){
    dp[x][y] += dprec(x + 1, y);
  }
  if(y + 1 < m){
    dp[x][y] += dprec(x, y + 1);
  }
  return dp[x][y];
}

int main() {
	cin.tie(0)->sync_with_stdio(0);
	cin.exceptions(cin.failbit);
#ifdef LOCAL_DEFINE
	freopen("input.txt", "r", stdin);
#endif
  cin >> n >> m;
  l = n + m - 1;
  rep(i, 0, n) rep(j, 0, m) cin >> v[i][j];
  ll k; cin >> k;
	rep(i, 0, l) ans[i] = '*';
	ans[0] = v[0][0];
	rep(i, 1, l) rep(j, 0, 26){
	  ans[i] = j + 'a';
	  memset(dp, -1, sizeof dp);
	  if(dprec(0, 0) >= k) break;
	  k -= dprec(0, 0);
	}
	cout << ans << '\n';
}

Compilation message (stderr)

kthpath.cpp: In function 'void usaco(std::string)':
kthpath.cpp:13:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   13 |   freopen((s+".in").c_str(), "r", stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kthpath.cpp:14:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   14 |   freopen((s+".out").c_str(), "w", stdout);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 100 / 100