题目
A Cubic number and A Cubic Number
题解
因为 a3−b3=(a−b)(a2+ab+b2) ,如果 a3−b3 为质数,那么 a−b=1,b=a+1 , 带入 a2+ab+b2 得 3b2+3b+1 ,然后预处理+二分就可以了
代码
#include <algorithm>
#include <bitset>
#include <cstring>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <climits>
#include <iostream>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
using namespace std;
const int MAX = 1000005;
long long pre[MAX];
int main(){
pre[0] = 0;
for(long long i=1;i<MAX;++i){
pre[i] = 3 * i * i + 3 * i + 1;
}
int n;
cin >> n;
for(int i=0;i<n;++i){
long long p;
cin >> p;
if(!binary_search(pre+1,pre+MAX,p))
cout << "NO" << endl;
else
cout << "YES" << endl;
}
return 0;
}