Submission #415321

#	Time	Username	Problem	Language	Result	Execution time	Memory
415321		JerryLiu06	Matching (CEOI11_mat)	C++17	100 / 100	853 ms	44144 KiB

mat

#include <bits/stdc++.h>
 
using namespace std;
 
using ll = long long;
using db = long double;
using str = string;
 
using pi = pair<int, int>;
using pl = pair<ll, ll>;
using pd = pair<db, db>;
 
using vi = vector<int>;
using vb = vector<bool>;
using vl = vector<ll>;
using vd = vector<db>;
using vs = vector<str>;
using vpi = vector<pi>;
using vpl = vector<pl>;
using vpd = vector<pd>;
 
#define mp make_pair
#define f first
#define s second

#define sz(x) (int)(x).size()
#define bg(x) begin(x)
#define all(x) bg(x), end(x)
#define sor(x) sort(all(x))
#define ft front()
#define bk back()
#define pb push_back
#define pf push_front
 
#define lb lower_bound
#define ub upper_bound
 
#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define F0R(i, a) FOR(i, 0, a)
#define ROF(i, a, b) for (int i = (b) - 1; i >= (a); i--)
#define R0F(i, a) ROF(i, 0, a)
#define EACH(a, x) for (auto& a : x)

const int MOD = 1e9 + 7;
const int MX = 1e6 + 10;
const ll INF = 1e18;

int N, M, S[2 * MX]; vi allM; int place[MX]; int tree[MX];

int pref[2 * MX]; vi ans;

// Binary Indexed Tree ~ O(lg N)

void update(int ind, int val) {
    while (ind <= M) { tree[ind] += val; ind += (ind & -ind); }
}
int query(int ind) {
    int res = 0; while (ind > 0) { res += tree[ind]; ind -= (ind & -ind); } return res;
}

// Variation on KMP Algorithm with BIT ~ O(N lg N) ?

void genPref() {
    int L = 1; // Left pointer of current suffix -- L is nondecreasing

    FOR(i, 1, N + M + 1) {
        if (S[i] == -1) { pref[i] = 0; while (L < i) update(S[L++], -1); L++; continue; }

        int j = pref[i - 1]; if (j == N) j = pref[j - 1];

        while (L < i - j) update(S[L++], -1);

        while (j > 0 && query(S[i]) != place[j]) {
            j = pref[j - 1]; while (L < i - j) update(S[L++], -1);
        }
        if (query(S[i]) == place[j]) j++; pref[i] = j; update(S[i], 1);

        if (pref[i] == N) ans.pb(i - 2 * N + 1);
    }
}

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

    cin >> N >> M; F0R(i, N) { int X; cin >> X; S[--X] = i + 1; }
    F0R(i, N) { place[i] = query(S[i]); update(S[i], 1); }
    
    S[N] = -1; F0R(i, N) update(S[i], -1); 

    FOR(i, N + 1, N + M + 1) cin >> S[i], allM.pb(S[i]);

    sort(all(allM)); allM.erase(unique(all(allM)), allM.end());
    FOR(i, N + 1, N + M + 1) S[i] = ub(all(allM), S[i]) - allM.bg();
    
    //F0R(i, N + M + 1) cout << S[i] << "\n";

    genPref(); cout << sz(ans) << "\n"; EACH(i, ans) cout << i << " ";
}

Compilation message (stderr)

mat.cpp: In function 'void genPref()':
mat.cpp:76:9: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   76 |         if (query(S[i]) == place[j]) j++; pref[i] = j; update(S[i], 1);
      |         ^~
mat.cpp:76:43: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
   76 |         if (query(S[i]) == place[j]) j++; pref[i] = j; update(S[i], 1);
      |                                           ^~~~

• Subtask 1: 9 / 9
• Subtask 2: 9 / 9
• Subtask 3: 9 / 9
• Subtask 4: 9 / 9
• Subtask 5: 9 / 9
• Subtask 6: 9 / 9
• Subtask 7: 9 / 9
• Subtask 8: 9 / 9
• Subtask 9: 8 / 8
• Subtask 10: 10 / 10
• Subtask 11: 10 / 10