【HDOJ】1405 The Last Practice

简单题，感觉求素数的算法太慢了。以前在SPOJ上交的效率要高很多。注意输出格式，容易PE。

#include <stdio.h>
#include <string.h>

#define MAXNUM 65536

int array[MAXNUM];
int prime[7000];
int nums[MAXNUM];

int main() {
    int case_n = 0;
    int n;
    int i, j, k;

    memset(array, 1, sizeof(array));
    k = 0;
    for (i=2; i<MAXNUM; ++i) {
        if (array[i]) {
            prime[k++] = i;
            for (j=2; j*i<MAXNUM; ++j)
                array[i*j] = 0;
        }
    }

    while (scanf("%d", &n) != EOF && n>0) {
        if (case_n)
            printf("\n");
        ++case_n;
        printf("Case %d.\n", case_n);
        memset(nums, 0, sizeof(nums));

        for (i=0; i<k && prime[i]<=n; ++i) {
            while (n%prime[i] == 0) {
                nums[prime[i]]++;
                n /= prime[i];
            }
        }

        for (i=2; i<MAXNUM; ++i)
            if (nums[i])
                printf("%d %d ", i, nums[i]);
        printf("\n");
    }


    return 0;
}