我是黄色恐龙大将军 参考代码

#include <bits/stdc++.h>
using namespace std;

typedef long long LL;
const int maxn = 100 + 100;

LL cal(LL x) {
    int ret = 0;
    while (x != 0) {
        ret = x % 10;
        x /= 10;
    }
    return ret;
}

int main() {
#ifdef ExRoc
    freopen("test.txt", "r", stdin);
#endif // ExRoc
    ios::sync_with_stdio(false);

    set<LL> st;
    LL tmp2 = 1;
    LL tmp5 = 1;
    for (int i = 0; i < 25; ++i) {
        tmp2 *= 2;
        tmp5 *= 5;
        cout << "i = " << i << ": " << cal(tmp2) * cal(tmp5) << endl;
        st.insert(cal(tmp2) * cal(tmp5));
    }
    int ans = 0;
    for (int x : st) {
        ans += x;
    }
    cout << ans << endl;

    return 0;
}