java - 在 LeetCode 质数挑战赛中找不到我的程序的修复程序

Question

我尝试了多种方法来更改 LeetCode 中的代码，但找不到修复方法，挑战是下一个:

<<计算小于非负数 n 的素数数量。

示例:

输入:10输出:4说明:小于 10 的素数有 4 个，分别是 2、3、5、7。>>

我的提案代码是下一个:

 import java.util.Scanner;
    class Solution {
        public int countPrimes(int n) {
        Scanner sc = new Scanner(System.in);
        int sum = 0;
        int cont = 0;
        int prime = 0;
        prime = sc.nextInt();
        int a[] = new int [prime];
        for(int i = 0; i < a.length; i++) {
            a[i] = i;
            cont = 0;
            
            for(int y = 1; y< a.length; y++) {
                if(a[i] % y == 0) {
                    cont ++;
                }
            }
            if (cont == 2) {
                sum ++;
            }
        }
        return sum;
    }
}

同时错误标记如下:

Submission Result: Compile Error More Details 
Line 7: error: cannot find symbol [in __Driver__.java] int ret = new Solution().countPrimes(param_1); ^ symbol: method countPrimes(int) location: class Solution
Run Code Status: Runtime Error
×
Run Code Result:
Your input
10
Your answer
java.util.NoSuchElementException
  at line 937, java.base/java.util.Scanner.throwFor
  at line 1594, java.base/java.util.Scanner.next
  at line 2258, java.base/java.util.Scanner.nextInt
  at line 2212, java.base/java.util.Scanner.nextInt
  at line 8, Solution.countPrimes
  at line 54, __DriverSolution__.__helper__
  at line 84, __Driver__.main
Show Diff
Runtime: N/A

请帮忙!

Answer 1

这也会通过:

public class Solution {
    public static final int countPrimes(int n) {
        // mapping for if the number is divisible by prime numbers, which would make that number a composite number
        boolean[] notPrime = new boolean[n];
        // counting prime numbers
        int count = 0;

        for (int i = 2; i < n; i++) {
            // If the index of notPrime would be false, we have a prime number, we go through the if, otherwise we continue
            if (notPrime[i] == false) {
                // Increment the number of prime numbers
                count++;

                // Look into future numbers
                for (int j = 2; i * j < n; j++) {
                    // find composite numbers and set their indices to true
                    notPrime[i * j] = true;
                }
            }
        }

        return count;
    }
}

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