见题: 我的代码:

#include <bits/stdc++.h>
using namespace std;
bool hw(long long int num)
{
    string str = to_string(num);
    string cubeStr = to_string(num);
    reverse(cubeStr.begin(), cubeStr.end());
    return cubeStr == str;
}
bool zs(long long int num)
{
    long long int r=1,l=num,mid;
    while(r<=l) {
        mid=(r+l)/2;
        if(mid*mid*mid==num) {
            return true;
        }
        if(mid*mid*mid>num) {
            l=mid-1;
        } else {
            r=mid+1;
        }
    }
    return false;
}
int main()
{
    long long int num;
    cin >> num;
    num++;
    while(num--) {
        if(zs(num)) {
            if(hw(num)) {
                cout<<num;
                return 0;
            }
        }
    }
    return 0;
}

结果:超时(40分)