http://acm.hdu.edu.cn/showproblem.php?pid=6441
Problem Description
people in USSS love math very much, and there is a famous math problem .
give you two integers n ,a ,you are required to find 2 integers b ,c such that a^n +b^n=c^n .
Input
one line contains one integer T ;(1≤T≤1000000)
next T lines contains two integers n ,a ;(0≤n≤1000 ,000 ,000,3≤a≤40000)
Output
print two integers b ,c if b ,c exits;(1≤b,c≤1000 ,000 ,000) ;
else print two integers -1 -1 instead.
Sample Input
1 2 3
Sample Output
4 5
根据费马大定理可知a^n+b^n=c^n,当n>2时,等式不成立,
所以只需要分析n=1和n=2的情况,
n=1,只需让b=1,c=a+b,即可,
n=2,根据费马大定理奇偶数列法则可知
当a为>=3的奇数时,a=2*n+1, c=n^2+(n+1)^2, b=c-1;
当a为>=4的偶数时,a=2*n+2, c=(n+1)^2+1, b=c-2;
Ac代码:
#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cmath>
using namespace std;
int a,n;
int main()
{
int t;
scanf("%d",&t);
while(t--){
scanf("%d%d",&n,&a);
int b,c;
if(n==2)
{
if(a>=3&&a%2==1)
{
int p=(a-1)/2;
c=p*p+(p+1)*(p+1);
b=c-1;
}
if(a>=4&&a%2==0)
{
int p=(a-2)/2;
c=(p+1)*(p+1)+1;
b=c-2;
}
}
else if(n==1)
{
b=1;
c=b+a;
}
else {
b=-1;
c=-1;
}
printf("%d %d\n",b,c);
}
}