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| import java.util.Arrays;
class Solution {
public int solution(int n) {
// Init isPrime array
boolean[] isPrime = new boolean[n+1];
Arrays.fill(isPrime, true);
isPrime[0] = false; // 0 is not prime
isPrime[1] = false; // 1 is not prime
// Find prime number
for (int i = 2; i <= n; i++) {
if (isPrime[i]) {
for (int j = 2*i; j <= n; j = j + i) {
isPrime[j] = false;
}
}
}
// Get prime number count
int count = 0;
for (int i = 0; i < isPrime.length; i++) {
if (isPrime[i]) {
count++;
}
}
return count;
}
}
|