hdu 6216-A Cubic number and A Cubic Number

Problem Description
A cubic number is the result of using a whole number in a multiplication three times. For example, 3×3×3=27 so 27 is a cubic number. The first few cubic numbers are 1,8,27,64 and 125. Given an prime number p. Check that if p is a difference of two cubic numbers.

Input
The first of input contains an integer T (1≤T≤100) which is the total number of test cases.
For each test case, a line contains a prime number p (2≤p≤1012).

Output
For each test case, output ‘YES’ if given p is a difference of two cubic numbers, or ‘NO’ if not.

Sample Input
10
2
3
5
7
11
13
17
19
23
29

Sample Output
NO
NO
NO
YES
NO
NO
NO
YES
NO
NO

x^3-y^3=(x-y)(x^2+xy+y^2)；
因为p为素数，x与y必相邻（不是全部，6^3-5^3=26就不满足）
所以x-y=1以及x^2+xy+y^2=p
代入消元得p=3x^2+3x+1

#include <iostream>#include <cstdio>#define LL long longusing namespace std;int main(){    int t;    scanf("%d",&t);    while(t--)    {        LL p;        scanf("%lld",&p);        int flag=0;        for(LL i=1;i<=1000001;i++)        {            if(3*i*i+3*i+1==p)            {                flag=1;                break;            }        }        if(flag)        {            printf("YES\n");        }        else        {            printf("NO\n");        }    }    return 0;}