59 lines
1.4 KiB
Java
59 lines
1.4 KiB
Java
package ProjectEuler;
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/**
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* By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13.
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* <p>
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* What is the 10 001st prime number?
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* <p>
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* link: https://projecteuler.net/problem=7
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*/
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public class Problem07 {
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public static void main(String[] args) {
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int[][] testNumbers = {
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{1, 2},
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{2, 3},
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{3, 5},
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{4, 7},
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{5, 11},
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{6, 13},
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{20, 71},
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{50, 229},
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{100, 541}
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};
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for (int[] number : testNumbers) {
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assert solution1(number[0]) == number[1];
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}
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}
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/***
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* Checks if a number is prime or not
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* @param number the number
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* @return {@code true} if {@code number} is prime
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*/
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private static boolean isPrime(int number) {
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if (number == 2) {
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return true;
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}
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if (number < 2 || number % 2 == 0) {
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return false;
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}
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for (int i = 3, limit = (int) Math.sqrt(number); i <= limit; i += 2) {
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if (number % i == 0) {
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return false;
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}
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}
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return true;
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}
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private static int solution1(int n) {
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int count = 0;
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int number = 1;
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while (count != n) {
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if (isPrime(++number)) {
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count++;
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}
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}
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return number;
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}
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} |