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;
}