lc2523.cpp

#include <vector>
#include <algorithm>
using namespace std;

class Solution {
    public:
    
        vector<int> closestPrimes(int left, int right) {
    
            int n = right;
            vector<bool> is_prime(n+1, true);
            is_prime[0] = is_prime[1] = false;
            for (int i = 2; i * i <= n; i++) {
                if (is_prime[i]) {
                    for (int j = i * i; j <= n; j += i)
                        is_prime[j] = false;
                }
            }
    
            vector<int> result;
            for(int n = left; n <= right && result.size() < 2; n++) {
                if (is_prime[n])
                    result.push_back(n);
            }
    
            if (result.size() < 2)
                return {-1,-1};
    
            return result;
    
        }
    
    };