题解 | 筛选法求素数

#include <stdio.h>

int main() {
    int n = 0;
    int arr[99] = { 0 };
    int index = 0;//用来找下标
    int count = 0;
    while (scanf("%d", &n) != EOF) {
        count = 0;
        for (int i = 0; i <= n; i++) {
            arr[i] = i;
        }
        for (int i = 2; i <= n; i++) {
            for (int j = 2; j <= n; j++) {
                if (arr[j] == i) {
                    index = j;//找到下标
                    break;
                }
            }
            //清零操作
            for (int a = index + 1; a <= n; a++) {
                if (arr[a] % i == 0 && arr[a] != 0) {
                    arr[a] = 0;
                    count++;
                }
            }

        }
        for (int i = 2; i <= n; i++) {
            if (arr[i] != 0) {
                printf("%d ", arr[i]);
            }
        }
        printf("\n");
        printf("%d\n", count);
    }
    return 0;
}