Submission #882017

#	Time	Username	Problem	Language	Result	Execution time	Memory
882017		vjudge1	K-th path (IZhO11_kthpath)	C++17	0 / 100	0 ms	344 KiB

kthpath

#include <bits/stdc++.h>
using namespace std;
#define sp << " " << 
#define int long long
#define vi vector<int>
#define F(xxx,yyy) for (int xxx=1;xxx<=yyy;xxx++)
#define pii pair<int,int>
const int N = 1e5+1,inf = 1e18;

int nck(int n,int k,int big) {
  bool fuck = 0;
  int dp[n+1][k+1];
  memset(dp,0,sizeof dp);
  dp[0][0] = 1;
  for (int i=1;i<=n && !fuck;i++) {
    for (int j=0;j<=k && !fuck;j++) {
      if (!j) {
        dp[i][j] = 1;
        continue;
      }
      if (dp[i-1][j-1]+dp[i-1][j] > big) {
        fuck = 1;
        break;
      }
      dp[i][j] = dp[i-1][j-1]+dp[i-1][j];
    }
  }
  if (!fuck && dp[n][k] <= big) return dp[n][k];
  return -1;
}


void solve() {
  int n,m;
  cin >> n >> m;
  char grid[n+1][m+1];
  F(i,n) {
    string s;
    cin >> s;
    F(j,m) grid[i][j] = s[j-1];
  }
  int k;
  cin >> k;
  int x = 1;
  int y = 1;
  string cur = "a";
  while (x<n || y<m) {
    if (x == n) {
      cur+=grid[x][++y];
      continue;
    }
    if (y == m) {
      cur+=grid[++x][y];
      continue;
    }
    if (grid[x][y+1] < grid[x+1][y]) {
      int wys = nck(n+m-x-y-1,n-x,k);
      if (wys==-1) {
        y++;
        cur+=grid[x][y];
        continue;
      }
      else {
        x++;
        cur+=grid[x][y];
        k-=wys;
        continue;
      }
    }
    else {
      int wys = nck(n+m-x-y-1,m-x,k);
      if (wys == -1) {
        x++;
        cur+=grid[x][y];
        continue;
      }
      else {
        y++;
        cur+=grid[x][y];
        k-=wys;
        continue;
      }
    }
  }
  cout << cur << endl;
}
    
                  
                             
signed main() { 
  ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
  #ifdef Local
  freopen("in","r",stdin);
  freopen("out","w",stdout);
  #endif
  int t = 1;
  //cin >> t;
	F(i,t) solve();
}

• Subtask 1: 0 / 100