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OI-codes/Codeforces/1586/A/A.cpp
2022-04-01 18:33:24 +08:00

54 lines
1.2 KiB
C++

#include <bits/stdc++.h>
using namespace std;
int t, n, a[105], sum, p1, p2;
bool is_prime[20005];
void Eratosthenes(int n) {
for (int i = 0; i <= n; i++) is_prime[i] = true;
is_prime[0] = is_prime[1] = false;
for (int i = 2; i <= n; i++) {
if (is_prime[i]) {
if (i * i <= n) {
for (int j = i * i; j <= n; j += i) {
is_prime[j] = false;
}
}
}
}
}
int main() {
std::ios::sync_with_stdio(false);
cin >> t;
Eratosthenes(20000);
while (t--) {
sum = 0;
p1 = p2 = -1;
cin >> n;
for (int i = 1; i <= n; i++) {
cin >> a[i];
if (a[i] == 1) p1 = i;
if (a[i] % 2) p2 = i;
sum += a[i];
}
cout << n - is_prime[sum] << endl;
if (!is_prime[sum]) {
for (int i = 1; i <= n; i++) {
cout << i << ' ';
}
} else if (p1 != -1) {
for (int i = 1; i <= n; i++) {
if (i != p1) cout << i << ' ';
}
} else {
for (int i = 1; i <= n; i++) {
if (i != p2) cout << i << ' ';
}
}
cout << endl;
}
return 0;
}