题解 | #小红的“质数”寻找#

根据首位进行分类，进1凑质数即可

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ui = unsigned;
using ulll = unsigned __int128;
using lll = __int128;
using db = double;
using ldb = long double;
using b20 = bitset<20>;

const int Inf = 0x3f3f3f3f;
const ll Linf = 0x3f3f3f3f3f3f3f3fLL;
const db Dinf = 1e18;
const int Maxm = 400005;
const int Maxn = 10005;
const int MOD[] = {998244353, 1000000007};

#define endl '\n'
//------------------------------------------------------------------

void solve() {
    string s;
    cin >> s;
    if (s[0] == '1') {
        if (s.size() == 1) {
            cout << 2 << endl;
            return;
        } else {
            cout << 2;
            for (ll i = 1; i < s.size(); ++i) cout << 0;
            cout << endl;
            return;
        }
    } else if (s[0] == '2') {
        if (s.size() == 1) {
            cout << 2 << endl;
            return;
        } else {
            cout << 3;
            for (ll i = 1; i < s.size(); ++i) cout << 0;
            cout << endl;
            return;
        }
    } else if (s[0] == '3') {
        if (s.size() == 1) {
            cout << 3;
            cout << endl;
            return;
        } else {
            cout << 4;
            for (ll i = 1; i < s.size() - 1; ++i) cout << 0;
            cout << 1 << endl;
            return;
        }
    } else if (s[0] == '4') {
        if (s.size() == 1) {
            cout << 5 << endl;
            return;
        } else {
            cout << 5;
            for (ll i = 1; i < s.size(); ++i) cout << 0;
            cout << endl;
            return;
        }
    } else if (s[0] == '5') {
        if (s.size() == 1) {
            cout << 5;
            cout << endl;
            return;
        } else {
            cout << 6;
            for (ll i = 1; i < s.size() - 1; ++i) cout << 0;
            cout << 1 << endl;
            return;
        }
    } else if (s[0] == '6') {
        if (s.size() == 1) {
            cout << 7;
            cout << endl;
            return;
        } else {
            cout << 7;
            for (ll i = 1; i < s.size(); ++i) cout << 0;
            cout << endl;
            return;
        }
    } else if (s[0] == '7') {
        if (s.size() == 1) {
            cout << 7;
            cout << endl;
            return;
        } else {
            cout << 8;
            for (ll i = 1; i < s.size() - 1; ++i) cout << 0;
            cout << 3 << endl;
            return;
        }
    } else if (s[0] == '8') {
        if (s.size() == 1) {
            cout << 11;
            cout << endl;
            return;
        } else {
            cout << 9;
            for (ll i = 1; i < s.size() - 1; ++i) cout << 0;
            cout << 2 << endl;
            return;
        }
    } else {
        if (s.size() == 1) {
            cout << 11;
            cout << endl;
            return;
        } else {
            cout << 10;
            for (ll i = 1; i < s.size() - 1; ++i) cout << 0;
            cout << 1 << endl;
            return;
        }
    }
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    ll _;
    cin >> _;
    while (_--) solve();

    return 0;
}cpp