Submission #1124182

#	Time	Username	Problem	Language	Result	Execution time	Memory
1124182		anhthi	K-th path (IZhO11_kthpath)	C++17	100 / 100	23 ms	32420 KiB

kthpath

#include <bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define ll long long
#define ull unsigned long long
#define mp(x, y) make_pair(x, y)
#define sz(v) ((int) (v).size())
#define all(v) (v).begin(), (v).end()
#define MASK(i) (1LL << (i))
#define BIT(x, y) (((x) >> (y)) & 1)
#define pb push_back
#define heap priority_queue
#define max_rng *max_element
#define min_rng *min_element
#define rep(i, n) for(int i = 1, _n = (n); i <= _n; ++i)
#define forn(i, a, b) for(int i = (a), _b = (b); i <= _b; ++i)
#define ford(i, a, b) for(int i = (a), _b = (b); i >= _b; --i)
#define mem(s, x) memset(s, x, sizeof (s))

template <class X, class Y>
    inline bool maximize(X &x, Y y) {
        return (x < y ? x = y, true : false);
    }

template <class X, class Y>
    inline bool minimize(X &x, Y y) {
        return (x > y ? x = y, true : false);
    }

template <class X>
    inline void compress(X &a) {
        sort(all(a));
        a.resize(unique(all(a)) - a.begin());
    }

template<class X>
    inline void printArr(vector<X> a, char spec = ' ', char line = '\n') {
        for (X val : a) cout << val << spec;
        cout << line;
    }

int ctz(ll x) { return __builtin_ctzll(x); }
int lg(ll x) { return 63 - __builtin_clzll(x); }
int popcount(ll x) { return __builtin_popcountll(x); }

// const ll oo = (ll) 1e17;
// const int INF = (int) 1e9 + 7, MOD = (int) 1e9 + 7;

// int add(int &x, int y) {
//     x += y;
//     if (x >= MOD) x -= MOD;
//     if (x < 0) x += MOD;
//     return x;
// }

// int mult(int x, int y) {
//     return 1LL * x * y % MOD;
// }

const ull oo = (ll) 9e18 + 10;
ull add(ull &x, ull y) {
    x += y;
    if (x >= oo) x = oo;
    return x;
}
ull mult(ull x, ull y) {
    return x >= oo / y ? oo : x * y;
}

const int N = 2e3 + 15;

int T;

int sub;
int n, m, q;
char a[N][N];

ull dp[N][N], dp_go[N][N];
vector<pair<int, int>> diag[2 * N];

void solve() {
    // cin >> sub;
    cin >> n >> m;
    rep(i, n) rep(j, m) {
        cin >> a[i][j];
    }   

    dp[n][m] = 1;
    ford(i, n, 1) ford(j, m, 1) {
        add(dp[i][j], dp[i + 1][j]);
        add(dp[i][j], dp[i][j + 1]);
    }

    rep(i, n) rep(j, m) {
        diag[i + j].pb(mp(i, j));
    }

    // rep(_, q) {
        ull k;
        cin >> k;

        memset(dp_go, 0, sizeof dp_go);

        string res;
        res += a[1][1];
        dp_go[2][1] = dp_go[1][2] = 1;

        vector<ull> value(26);
        forn(len, 2, n + m - 1) {
            fill(all(value), 0);
            for (pair<int, int> i : diag[len + 1]) {
                int x = i.first, y = i.second;
                add(value[a[x][y] - 'a'], mult(dp_go[x][y], dp[x][y]));
            }
            forn(i, 0, 25) {
                if (value[i] < k) {
                    k -= value[i];
                }
                else {
                    res += char(i + 'a');
                    break;
                }
            }
            for (pair<int, int> i : diag[len + 1]) {
                int x = i.first, y = i.second;
                if (a[x][y] != res.back()) continue;
                add(dp_go[x + 1][y], dp_go[x][y]);
                add(dp_go[x][y + 1], dp_go[x][y]);
            }
        }

        cout << res << '\n';   
    // }

    return;
}

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

    #define TASK "task"
    if (fopen(TASK".inp", "r")) {
        freopen(TASK".inp", "r", stdin);
        freopen(TASK".out", "w", stdout);
    }
    T = 1;
    // cin >> T;
    while (T--) {
        solve();
    }

    return 0;
}

Compilation message (stderr)

kthpath.cpp: In function 'int main()':
kthpath.cpp:147:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  147 |         freopen(TASK".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
kthpath.cpp:148:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  148 |         freopen(TASK".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 100 / 100