UAIC 2024 SIII P3

#include <iostream>
#include <algorithm>
// using namespace std;   error: reference to 'pair' is ambiguous
const int MAXW = 50257;
const int MAXN = 1000000;
typedef struct pair {
    int w1;// 0 <= w1 < MAXW
    int w2;// 0 <= w2 < MAXW
    bool operator == (pair b)
    {
        return (w1 == b.w1 && w2 == b.w2);
    }
    bool operator < (pair b)
    {
        if(w1 != b.w1)
            return (w1 < b.w1);
        return (w2 < b.w2);
    }
}pair;

int mostLikely(int *V, int N, pair P)
{
    int sol = 0, maxiAp = 0;
    int frecv[MAXW] = {0};
    for(int i = 2;i<N;i++)
        if(V[i-2] == P.w1 && V[i-1] == P.w2)
        {
            frecv[V[i]]++;
            if(frecv[V[i]] > maxiAp)
                sol = V[i], maxiAp = frecv[V[i]];
        }
    return sol;
}
bool cmp(pair a, pair b)
{
    if(a.w1 != b.w1)
        return a.w1 < b.w1;
    return a.w2 < b.w2;
}
int pairs(int *V, int N, pair *Pairs)
{
    for(int i = 0;i < N - 1;i++)
        Pairs[i] = {V[i], V[i+1]};

    std::sort(Pairs, Pairs + N - 1, cmp);

    int L = 0;

    for(int i = 1;i < N - 1;i++)
    {
        if(! (Pairs[i] == Pairs[i-1]) )
            Pairs[++L] = Pairs[i];
    }
    return L + 1;
}
int pairIndex(pair *Pairs, int L, pair P)
{
    int st = 0, dr = L - 1, mid;
    while(st <= dr)
    {
        mid = (st + dr) / 2;
        if(Pairs[mid] == P)
            return mid;
        if(Pairs[mid] < P)
            st = mid + 1;
        else dr = mid - 1;
    }
    return -1;
}
void learn(int *V, int N, pair *Pairs, int L, int *Next)
{
    for(int i = 0;i < L;i++)
        Next[i] = mostLikely(V,N,Pairs[i]);
}
void generate(int *V, int N, int K, int *R, int X, int Y)
{
    // Declaram si calculam Pairs si Next
    pair Pairs[N - 1];
    int L = pairs(V,N,Pairs);
    int Next[L];
    learn(V,N,Pairs,L,Next);

    // Generam textul.
    R[0] = X, R[1] = Y;
    for(int i = 2;i < K;i++)
    {
        pair c = {R[i-2], R[i-1]};
        int poz = pairIndex(Pairs,L,c);
        if(poz != -1)
            R[i] = Next[poz];
        else R[i] = 0;
    }
}
int main()
{
    return 0;
}