PAT 1085. Perfect Sequence

#include <cstdio>

#include <climits>

#include <cstdlib>

#include <algorithm>

using namespace std;



int main() {

    int N,p;

    scanf("%d%d", &N, &p);

    if (N < 1) {

        printf("%d\n", 0);

        return 0;

    }

    vector<int> seq(N);

    

    for (int i=0; i<N; i++) {

        scanf("%d", &seq[i]);

    }

    

    if (N < 2) {

        printf("%d\n", 1);

        return 0;

    }

    

    sort(seq.begin(), seq.end());

    

    long long m = seq[0];

    long long M = seq[0];

    

    int i = 0, j = 1;

    int max_len = 1;

    int cur_len = 1;

    while (i < j && j < N) {

        m = seq[i];

        M = seq[j];

        

        if (M <= m * p) {

            cur_len = j - i + 1;

            j++;

        } else {

            while (M > m * p) {

                m = seq[++i];

            }

        }

        

        if (cur_len > max_len) {

            max_len = cur_len;

        }

    }

    

    printf("%d\n", max_len);

    return 0;

}