POJ 1733 Parity game（种类并查集）

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<algorithm>
 4 using namespace std;
 5 const int maxn = 2*5005;
 6 
 7 int n,q,tot;
 8 int p[maxn],re[maxn],a[maxn];  //0表示偶，1表示奇
 9 
10 struct node
11 {
12     int l, r;
13     char s[5];
14 }query[maxn];
15 
16 int finds(int x)
17 {
18     if(p[x]==x)  return x;
19     int tmp = p[x];
20     p[x] = finds(p[x]);
21     re[x] = (re[x]+re[tmp])%2;
22     return p[x];
23 }
24 
25 void unions(int l,int r,int x, int y,int tmp)
26 {
27     if(x<y)
28     {
29         p[x] = y;
30         re[x] = (re[r]-re[l]+tmp+2)%2;
31     }
32     else
33     {
34         p[y] = x;
35         re[y] = (re[l] - re[r]-tmp+2)%2;
36     }
37 }
38 
39 int main()
40 {
41     //freopen("in.txt","r",stdin);
42     tot = 0;
43     scanf("%d%d",&n,&q);
44     for(int i=0;i<=maxn;i++)  {p[i] = i;re[i]=0;}
45     for(int i=1;i<=q;i++)
46     {
47         scanf("%d%d%s",&query[i].l,&query[i].r,query[i].s);
48         query[i].l--;
49         a[++tot] = query[i].l;
50         a[++tot] = query[i].r;
51     }
52     sort(a+1,a+tot+1);
53     int num = unique(a+1,a+tot+1)-(a+1);
54     int i;
55     for(i=1;i<=q;i++)
56     {
57         int l = lower_bound(a+1,a+num+1,query[i].l)-(a+1);
58         int r = lower_bound(a+1,a+num+1,query[i].r)-(a+1);
59         int x = finds(l);
60         int y = finds(r);
61         int tmp = 0;
62         if(query[i].s[0]==‘o‘)   tmp = 1;
63         if(x==y)
64         {
65 
66             if((re[l]-re[r]+2)%2!=tmp)  break;
67         }
68         else
69         {
70             unions(l,r,x,y,tmp);
71         }
72     }
73     printf("%d\n",i-1);
74     return 0;
75 }