C - 343
https://atcoder.jp/contests/abc343/tasks/abc343_c
思路
先找出最大三次方数,次数小于或者等于 n,
参考:
在三次方根的可能范围内,使用二分查找法,定位最大的三次方根
https://www.cnblogs.com/Ghost-Knight/p/17970849
从此最大的三次方根开始,向下枚举, 枚举过程中对 三次方数进行是否回文的判定,
如果是回文,则停止。
Code
https://atcoder.jp/contests/abc343/submissions/50830008
ll n; ll low = 0; ll high = 1000000; int main() { cin >> n; ll left = 0; ll right = high; while(left < right-1){ // cout << "left="<<left << " right="<<right<<endl; ll middle = (left + right) / 2; ll cubic = middle*middle*middle; if (cubic == n){ left = middle; break; } else if (cubic < n){ left = middle; } else { right = middle; } } // cout << "left = " << left << endl; for (ll i=left; i>=0; i--){ ll cubic = i*i*i; ll cubic_origin = cubic; vector<int> digits; while(cubic){ int r = cubic%10; digits.push_back(r); cubic = cubic / 10; } // cout << "digits ====" << endl; // for(auto one: digits){ // cout << one << " "; // } // cout << endl; bool ishuiwen = true; int left = 0; int right = digits.size() - 1; while(left < right){ // cout << "digits[left]="<<digits[left]<< endl; // cout << "digits[right]="<<digits[right]<< endl; if (digits[left] != digits[right]){ ishuiwen = false; break; } left++; right--; } // cout << "ishuiwen=" << ishuiwen << endl; if (ishuiwen){ cout << cubic_origin << endl; break; } } return 0; }
标签:cubic,ll,方根,abc343,https,343 From: https://www.cnblogs.com/lightsong/p/18049476