53 lines
1.3 KiB
Kotlin
53 lines
1.3 KiB
Kotlin
class SequenceMaster(n: Int) {
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val primes = mutableListOf<Int>()
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init {
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primes.add(2)
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for (i in 3..n step 2) {
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var flag = true
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for (p in primes) {
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if (p * p > i) {
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break
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}
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if (i % p == 0) {
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flag = false
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break
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}
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}
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if (flag) {
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primes.add(i)
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}
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}
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}
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fun request(a: Int, b: Int): Int {
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val pa = primes.binarySearch(a)
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val pb = primes.binarySearch(b)
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return if (a == 1) {
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1
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} else {
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0
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} + if (pa >= 0 && pb >= 0) {
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pb - pa + 1
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} else if (pa < 0 && pb >= 0) {
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pb - (-pa - 1) + 1
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} else if (pa >= 0) {
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(-pb - 1) - pa
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} else {
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(-pb - 1) - (-pa - 1)
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}
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}
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}
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fun main() = with(System.`in`.bufferedReader()) {
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val (n, m) = this.readLine().split(' ').map { it.toInt() }
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val seq = SequenceMaster(n)
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System.out.bufferedWriter().use { bw ->
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repeat(m) {
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val (a, b) = this.readLine().split(' ').map { it.toInt() }
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bw.write("${seq.request(a, b)}\n")
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}
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}
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} |