函数goldSieve运行后，gb[4]的值为true。

cpp
复制
1#include 
2using namespace std;
3const int N = 5e3+10;
4bool st[N], gb[N];
5int primes[N], idx;
6void lineSieve() {
7for (int i = 2; i < N; i++) {
8
9    if (!st[i]) {
10
11        primes[idx++] = i;
12
13    }
14
15    for (int j = 0; j < idx && primes[j] <= N / i; j++) {
16
17        st[i*primes[j] * i] = 1;
18
19        if (i % primes[j] == 0) {
20
21            break;
22
23        }
24
25    }
26
27}
28
29
30}
31void goldSieve() {
32for (int i = 1; i < idx; i++) {
33
34    for (int j = i; j < idx && primes[i] <= N - primes[j]; j++) {
35
36        gb[primes[i] + primes[j]] = 1;
37
38    }
39
40}
41
42
43}
44int main() {
45lineSieve();
46
47goldSieve();
48
49int Q;
50
51cin >> Q;
52
53while (Q--) {
54
55    int t;
56
57    scanf("%d", &t);
58
59    if (gb[t]) {
60
61        printf("okk\n");
62
63    } else {
64
65        printf("something wrong\n");
66
67    }
68
69}
70
71return 0;
72
73}