1065 单身狗 (25 分)

#include<stdio.h>
int cmp(const void *a, const void *b)
{
    return *(int *)a - *(int *)b;
}

int main()
{
    int cp[100002] = {0}, singal[100002], other[100002];
    int N, i, M, len=0;
    scanf("%d", &N);

    for(i=0; i<N; i++)\
    {
        int a, b;
        scanf("%d %d", &a, &b);
        cp[a] = 1;
        cp[b] = 1;
        other[a] = b;
        other[b] = a;
    }

    scanf("%d", &M);
    for(i=0; i<M; i++)
    {
        int temp;
        scanf("%d", &temp);
        if(cp[temp] == 1)
        {
            cp[temp] ++;
        }
        if(cp[temp] == 0)
        {
            singal[len++] = temp;
        }
    }
    for(i=0; i<100001; i++)
    {
        if(cp[i] == 1 && cp[other[i]] == 2)
        {
            singal[len++] = other[i];
        }

    }

    qsort(singal, len, sizeof(singal[0]), cmp);
    printf("%d", len);
    if(len != 0)
    {
        printf("\n%05d", singal[0]);
        for(i=1; i<len; i++)
            printf(" %05d", singal[i]);

    }


}