POJ 4026 Eve 并查集 好题

哈哈

#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
#define maxn 300003
int vis[maxn];
struct node
{
    int sex, fa, de, DNA;  // sex性别，fa父亲节点， de是不是死了；
}p[maxn];

int a[maxn];
int n, m, k;
int find(int x)
{
    return p[x].fa == x ? x : p[x].fa = find(p[x].fa);
}

void merge(int x, int y)
{
    int rx = find(x);
    int ry = find(y);
    if(rx != ry)
        p[ry].fa = rx;
}
int main()
{
    int i;
    int x, y, len, sum;
    char buf[555];
    while( ~scanf("%d", &n))
    {
        for(i = 1; i <= maxn - 1; i++)
        {
            p[i].fa = i;
            p[i].de = 0;
            p[i].DNA = -1;
        }

        for(i = 1; i <= n; i++)
        {
            scanf("%s", buf);
            if(buf[0] == 'M')
                p[i].sex = 0;
            else 
                p[i].sex = 1;
        }
        scanf("%d", &m);
        getchar();
        while(m--)
        {
            gets(buf);
            len = strlen(buf);
            if(buf[0] == '-')
            {
                sum = 0;
                for(i = 1; i < len; i++)
                    sum = sum * 10 + buf[i] - '0';
                p[sum].de = 1;
            }
            else if(buf[len-1] == 'F' || buf[len-1] == 'M')
            {
                i = 0; x = y = 0;
                char c = buf[len-1];
                while(buf[i] != ' ') x = x * 10 + buf[i] - '0', i++;
                i++;
                while(buf[i] != ' ') y = y * 10 + buf[i] - '0', i++;
                if(c == 'F') p[++n].sex = 1;
                else p[++n].sex = 0;
                if(p[x].sex == 1)
                    merge(x, n);
                else
                    merge(y, n);
            }
        }
        scanf("%d", &k);
        while(k--)
        {
            scanf("%d%d", &x, &y);
            int rx = find(x);
            p[rx].DNA = y;
        }
        int num = 0;
        for(i = 1; i <= n; i++)
            if(!p[i].de)
                a[num++] = find(i);
        sort(a, a + num);
        num = unique(a, a + num) - a;
        if(num == 1)
            puts("YES");
        else
        {
            int cnt = 0;
            for(i = 0; i < num; i++)
                if(p[a[i]].DNA == -1) cnt++;
            if(cnt > 0) 
            {
                int ans = -1;
                for(i = 0; i < num; i++)
                {
                    if(p[a[i]].DNA == -1) continue;
                    if(ans == -1) ans = p[a[i]].DNA;
                    else if(ans != p[a[i]].DNA) break;
                }
                if(i == num) puts("POSSIBLY");
                else puts("NO");
            }
            else if(cnt == 0)
            {
                for(i = 1; i < num; i++)
                    if(p[a[0]].DNA != p[a[i]].DNA)
                        break;
                if(i == num) puts("YES");
                else puts("NO");
            }
        }
    }
    return 0;
}