A Simple Problem
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65535/32768 K (Java/Others)Total Submission(s): 474 Accepted Submission(s): 142
Problem Description
For a given positive integer n, please find the smallest positive integer x that we can find an integer y such that y^2 = n +x^2.
Input
The first line is an integer T, which is the the number of cases.
Then T line followed each containing an integer n (1<=n <= 10^9).
Then T line followed each containing an integer n (1<=n <= 10^9).
Output
For each integer n, please print output the x in a single line, if x does not exit , print -1 instead.
Sample Input
2 2 3
Sample Output
-1 1
Author
HIT
Source
Recommend
lcy
解法:
x^2+n=y^2
n=y^2-x^2=(y-x)*(y+x)
所以,可以枚举y-x的值来确定y+x
然后通过不断更新x的值来获得最小的ans
我的代码:
import java.math.*; import java.io.*; import java.util.*; public class Main { public static void main(String arg[]) { Scanner cin=new Scanner(System.in); int t,T,n,i,ans; int a,b,x,y; T=cin.nextInt(); for(t=1;t<=T;t++) { n=cin.nextInt(); ans=1999999999; for(i=1;i*i<=n;i++) { if(n%i==0) { a=i; b=n/i; if(b-a>0) { if((a+b)%2==0) { if((b-a)%2==0) { x=(b-a)/2; y=(a+b)/2; if(x<ans) ans=x; } } } } } if(ans>=1999999999) System.out.println("-1"); else System.out.println(ans); } } }