团体程序设计天梯赛 L1-006. 连续因子

Two ways:

1.接近O(n)

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main()
{
    long n,i,j,k,num=0,b;
    scanf("%ld",&n);
    for (i=2;i<=(long)sqrt(n);i++)
    {
        k=n;
        for (j=i;;j++)
            if (k%j==0)
                k=k/j;
            else
                break;
        if (j-i>num)
        {
            num=j-i;
            b=i;    
        }
    }
    if (num==0)
    {
        num=1;
        b=n;
    }
    printf("%ld
",num);
    for (i=b;i<b+num;i++)
    {
        printf("%ld",i);
        if (i!=b+num-1)
            printf("*");
    }
    return 0;
}

2.O(kn) 会超时

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main()
{
    long n,i,j,k,num=0,b;
    scanf("%ld",&n);
    for (i=2;i<=(long)sqrt(n);i++)
    {
        k=n;
        for (j=i;;j++)
            if (k%j==0)
                k=k/j;
            else
                break;
        if (j-i>num)
        {
            num=j-i;
            b=i;    
        }
    }
    if (num==0)
    {
        num=1;
        b=n;
    }
    printf("%ld
",num);
    for (i=b;i<b+num;i++)
    {
        printf("%ld",i);
        if (i!=b+num-1)
            printf("*");
    }
    return 0;
}

#include <stdio.h>#include <stdlib.h>#include <math.h>
int main(){long n,i,j,k,num=0,b;scanf("%ld",&n);for (i=2;i<=(long)sqrt(n);i++){k=n;for (j=i;;j++)if (k%j==0)k=k/j;elsebreak;if (j-i>num){num=j-i;b=i;}}if (num==0){num=1;b=n;}printf("%ld ",num);for (i=b;i<b+num;i++){printf("%ld",i);if (i!=b+num-1)printf("*");}return 0;}