Code Refactoring
Time Limit: 2 seconds
| "Harry, my dream is a code waiting to be broken. Break the code, solve the crime." |
Agent Cooper
Several algorithms in modern cryptography are based on the fact that factoring large numbers is difficult. Alicia and Bobby know this, so they have decided to design their own encryption scheme
based on factoring. Their algorithm depends on a secret code, K, that Alicia sends to Bobby before sending him an encrypted message. After listening carefully to Alicia's description, Yvette says, "But if I can intercept K and
factor it into two positive integers, A and B, I would break your encryption scheme! And the K values you use are at most 10,000,000. Hey, this is so easy; I can even factor it twice, into two different pairs
of integers!"
Input
The first line of input gives the number of cases, N (at most 25000). N test cases follow. Each one contains the code, K, on a line by itself.
Output
For each test case, output one line containing "Case #x: K = A * B = C * D", where A, B, C and D are
different positive integers larger than 1. A solution will always exist.
| Sample Input | Sample Output |
3 120 210 10000000 |
Case #1: 120 = 12 * 10 = 6 * 20 Case #2: 210 = 7 * 30 = 70 * 3 Case #3: 10000000 = 10 * 1000000 = 100 * 100000 |
把一个数分解成两个数的乘积。水题
#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;
int main ()
{
int k,t,a,b,c,d,i;
cin>>t;
for (i=1; i<=t; i++)
{
cin>>k;
int j;
for (j=2; j<k; j++)
if (k%j==0)
{
a=j;
b=k/j;
break;
}
for (j=a+1; j<k; j++)
if (k%j==0)
{
c=j;
d=k/j;
break;
}
printf("Case #%d: %d = %d * %d = %d * %d\n",i,k,a,b,c,d);
}
}