https://www.luogu.com.cn/problem/P10901

时间复杂度$\displaystyle \large O(n\log_{2}n\ \times C)$
这道题unordered_map会卡常，要么用map，要么用数组

#include <iostream>
#include <map>
#include <algorithm>

using namespace std;

const int N = 2e5 + 10;

int a[N];
int n;
map<char, int> mp = {{'0', 1}, {'4', 1}, {'6', 1}, {'9', 1}, {'8', 2}};
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);

    cin >> n;

    for (int i = 0; i < n; i++)
        cin >> a[i];

    sort(a, a + n, [](int a, int b)
         {
        int na = 0, nb = 0;
        for(auto ss : to_string(a))
            if(mp.count(ss))
                na += mp[ss];

        for(auto ss : to_string(b))
            if(mp.count(ss))
                nb += mp[ss];

        return na == nb ? a < b : na < nb; });

    for (int i = 0; i < n; i++)
        cout << a[i] << ' ';

    return 0;
}

或

#include <iostream>
#include <algorithm>

using namespace std;

const int N = 2e5 + 10;

int a[N];
int n;
int mp[] = {1, 0, 0, 0, 1, 0, 1, 0, 2, 1,};
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);

    cin >> n;

    for (int i = 0; i < n; i++)
        cin >> a[i];

    sort(a, a + n, [](int a, int b)
         {
        int aa = a, bb = b;
        int na = 0, nb = 0;
        while(aa) {
            int nn = aa % 10;
            na += mp[nn];
            aa /= 10;
        }

        while(bb) {
            int nn = bb % 10;
            nb += mp[nn];
            bb /= 10;
        }

        return na == nb ? a < b : na < nb; });

    for (int i = 0; i < n; i++)
        cout << a[i] << ' ';

    return 0;
}