c033: Prime Cuts、UVA 406

#include<stdio.h>

int primes[] = {1,2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97,101,103,107,109,113,127,131,137,139,149,151,157,163,167,173,179,181,191,193,197,199,211,223,227,229,233,239,241,251,257,263,269,271,277,281,283,293,307,311,313,317,331,337,347,349,353,359,367,373,379,383,389,397,401,409,419,421,431,433,439,443,449,457,461,463,467,479,487,491,499,503,509,521,523,541,547,557,563,569,571,577,587,593,599,601,607,613,617,619,631,641,643,647,653,659,661,673,677,683,691,701,709,719,727,733,739,743,751,757,761,769,773,787,797,809,811,821,823,827,829,839,853,857,859,863,877,881,883,887,907,911,919,929,937,941,947,953,967,971,977,983,991,997} ;

int main(){
    int N, C ;
    int i ;

    while(scanf("%d %d", &N, &C)==2){
        int count = 0 ;
        for(i=0 ; i<sizeof(primes)/sizeof(int) ; ++i){
            if(primes[i]<=N) count++ ;
            else break ;
        }
        int C_new = (count%2 ? 2*C-1 : 2*C ) ;
        int low, high ;
        if(C_new>count) {
            low = 0, high = count-1 ;
        }
        else{
            if(count%2){
                int mid = count/2 ;
                low = mid-(C-1) ;
                high = mid+(C-1) ;
            }
            else{
                int mid1 = count/2-1 ;
                int mid2 = count/2 ;
                low = mid1-(C-1) ;
                high = mid2+(C-1) ;
            }
        }
        printf("%d %d:", N, C) ;
        for(i=low ; i<=high ; ++i)
            printf(" %d",primes[i]) ;
        printf("\n\n") ;
    }
    return 0 ;
}