Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 28661 Accepted Submission(s): 11402
seed(x+1) = [seed(x) + STEP] % MOD
where '%' is the modulus operator.
Such a function will generate pseudo-random numbers (seed) between 0 and MOD-1. One problem with functions of this form is that they will always generate the same pattern over and over. In order to minimize this effect, selecting the STEP and MOD values carefully can result in a uniform distribution of all values between (and including) 0 and MOD-1.
For example, if STEP = 3 and MOD = 5, the function will generate the series of pseudo-random numbers 0, 3, 1, 4, 2 in a repeating cycle. In this example, all of the numbers between and including 0 and MOD-1 will be generated every MOD iterations of the function. Note that by the nature of the function to generate the same seed(x+1) every time seed(x) occurs means that if a function will generate all the numbers between 0 and MOD-1, it will generate pseudo-random numbers uniformly with every MOD iterations.
If STEP = 15 and MOD = 20, the function generates the series 0, 15, 10, 5 (or any other repeating series if the initial seed is other than 0). This is a poor selection of STEP and MOD because no initial seed will generate all of the numbers from 0 and MOD-1.
Your program will determine if choices of STEP and MOD will generate a uniform distribution of pseudo-random numbers.
15 20
63923 99999
15 20 Bad Choice
63923 99999 Good Choice
#include<iostream>
#include<stdio.h>
#include<algorithm>
using namespace std;
#define N 100000
int main()
{
int step,mod;
while(scanf("%d%d",&step,&mod)!=EOF)
{
int a[N],m=;
a[]=;
for(int i=;i<mod;i++)
{
a[i]=(a[i-]+step)%mod;
}
sort(a,a+mod);
for(int i=;i<mod;i++)
{
if(a[i]!=i)
{
m=;
break;
}
}
if(m==)
{
printf("%10d%10d",step,mod);
printf(" Bad Choice\n");
}
else
{
printf("%10d%10d",step,mod);
printf(" Good Choice\n");
}
printf("\n");
}
return ;
}
或者(判断两个数是否互质)
#include<stdio.h>
int hz(int t,int m)
{
for(int i=;i<=t&&i<=m;i++)
if(t%i==&&m%i==)
return ;
return ;
}
int main()
{
int t,m;
while(scanf("%d%d",&t,&m)!=EOF)
{
if(hz(t,m))
printf("%10d%10d Good Choice\n\n",t,m);
else
printf("%10d%10d Bad Choice\n\n",t,m);
}
}