#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define fi first
#define se second
#define ll long long
#define ld long double
#define sz(x) ((int)(x).size())
#define all(x) (x).begin(), (x).end()
#define pb push_back
#define mpp make_pair
#define ve vector
using namespace std;
using namespace __gnu_pbds;
template<class T> using oset = tree<T,null_type,less<T>,rb_tree_tag,tree_order_statistics_node_update>;
const ll inf = 1e18; const int iinf = 1e9;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
template <typename T> inline bool chmin(T& a, T b) { return (a > b ? a = b, 1 : 0); }
template <typename T> inline bool chmax(T& a, T b) { return (a < b ? a = b, 1 : 0); }
inline void solve() {
/*
#ifndef LOCAL
const string NAME = "kthpath";
ifstream cin(NAME + ".in");
ofstream cout(NAME + ".out");
#endif
*/
int n, m;
cin >> n >> m;
ve<ve<char>> a(n, ve<char>(m));
for (auto &i : a) for (auto &j : i) cin >> j;
ve<ve<ll>> dp(n, ve<ll> (m));
dp[n - 1][m - 1] = 1;
for (int i = n - 1; ~i; --i) {
for (int j = m - 1; ~j; --j) {
if (i + 1 < n) dp[i][j] += dp[i + 1][j];
if (j + 1 < m) dp[i][j] += dp[i][j + 1];
}
}
ll k;
cin >> k;
string result(1, a[0][0]);
map<string,ve<array<ll,3>>> cand;
cand[string(1, a[0][0])] = {{dp[0][0], 0, 0}};
while (sz(result) < n + m - 1) {
map<string,ve<array<ll,3>>> cur;
string S = cand.begin()->fi;
for (auto &[ways, x, y] : cand.begin()->se) {
if (x + 1 < n) {
cur[S + a[x + 1][y]].pb({dp[x + 1][y], x + 1, y});
}
if (y + 1 < m) {
cur[S + a[x][y + 1]].pb({dp[x][y + 1], x, y + 1});
}
}
for (auto &[str, V] : cur) {
auto vec = V;
ve<array<ll,3>> c;
for (int i = 0; i < sz(vec); ++i) {
if (!sz(c) || mpp(c.back()[1], c.back()[2]) != mpp(vec[i][1], vec[i][2])) c.pb(vec[i]);
else c.back()[0] += vec[i][0];
}
V = c;
}
map<string,ve<array<ll,3>>> nw;
for (auto &[str, vec] : cur) {
ll tot = 0;
for (auto &[ways, x, y] : vec) tot += ways;
if (k > tot) {
k -= tot;
}
else {
nw[str] = vec;
break;
}
}
swap(cand, nw);
result = cand.begin()->fi;
}
cout << result;
}
signed main() {
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
int q = 1; // cin >> q;
while (q--) solve();
cerr << fixed << setprecision(3) << "Time execution: " << (double)clock() / CLOCKS_PER_SEC << endl;
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
340 KB |
Output is correct |
| 2 |
Correct |
1 ms |
212 KB |
Output is correct |
| 3 |
Correct |
1 ms |
328 KB |
Output is correct |
| 4 |
Runtime error |
3 ms |
528 KB |
Execution killed with signal 6 |
| 5 |
Halted |
0 ms |
0 KB |
- |
