백준 1456 거의 소수 java solution

mong3125/정수론/BOJ1456_거의소수구하기.java

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+package 정수론;
+
+import java.util.Arrays;
+import java.util.Scanner;
+
+public class BOJ1456_거의소수구하기 {
+    static long A, B;
+    static boolean[] isPrime;
+    public static void main(String[] args) {
+        // 입력
+        Scanner sc = new Scanner(System.in);
+        A = sc.nextLong();
+        B = sc.nextLong();
+        isPrime = new boolean[10000001];
+
+        Arrays.fill(isPrime, true);
+        isPrime[0] = false;
+        isPrime[1] = false;
+
+        for (int i = 2; i < 10000001; i++) {
+            if (!isPrime[i]) continue;
+
+            for (int j = i+i; j < 10000001; j += i) {
+                isPrime[j] = false;
+            }
+        }
+
+        int count = 0;
+        int max = (int) Math.min(10000001, Math.sqrt(B));
+        for (int i = 2; i < max; i++) {
+            if (isPrime[i]) {
+                long now = i;
+                while ((double) i <= (double) B / (double) now) {
+                    if ((double) i >= (double) A / (double) now) count += 1;
+                    now *= i;
+                }
+            }
+        }
+
+        System.out.println(count);
+    }
+}