solving problems 9

插入乘号

二进制枚举，枚举乘号的位置

#include <iostream>
#include <cstring>
#include <algorithm>

using namespace std;

typedef long long LL;

signed main()
{
    ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
    
    int n, m;
    string s;
    cin >> n >> m >> s;
    int cnt = n - 1;
    LL ans = 0;
    for (int i = 0; i < 1 << cnt; i ++)
    {
        int t = 0;
        for (int j = 0; j < cnt; j ++)
        {
            t += i >> j & 1;
        }
        
        if (t == m)
        {
            LL res = 1;
            string str = s.substr(0, 1);
            for (int j = 0; j < cnt; j ++)
            {
                if (i >> j & 1)
                {
                    res *= stoll(str);
                    str = s.substr(j + 1, 1);
                }
                else    
                {
                    str += s[j + 1];
                }
            }
            res *= stoll(str);
            ans = max(ans, res);
        }
    }
    
    cout << ans << endl;
}