poj1733Parity game

 1 #include <iostream>
 2 #include <cstring>
 3 #include <cstdio>
 4 #include <algorithm>
 5 using namespace std;
 6 const int MAX = 5010;
 7 int a[2*MAX],father[2*MAX],r[2*MAX];
 8 struct Node
 9 {
10     int u,v;
11     char str[10];
12 };
13 Node que[MAX];
14 int n,m,cnt;
15 int Bin(int x)
16 {
17     int r = cnt - 1;
18     int l = 0;
19 
20     while(r >= l)
21     {
22         int mid = (r + l) / 2;
23         if(a[mid] > x)
24             r = mid - 1;
25         else if(a[mid] < x)
26             l = mid + 1;
27         else
28             return mid;
29     }
30     return -1;
31 }
32 int find_father(int x)
33 {
34     if(father[x] == x)
35         return x;
36     int t = find_father(father[x]);
37     r[x] = r[x] ^ r[father[x]];
38     return father[x] = t;
39 }
40 int main()
41 {
42     while(scanf("%d%d",&n,&m) != EOF)
43     {
44         cnt = 0;
45         for(int i = 1; i <= m; i++)
46         {
47             scanf("%d%d%s", &que[i].u,&que[i].v,que[i].str);
48             que[i].u --;
49             a[cnt++] = que[i].u;
50             a[cnt++] = que[i].v;
51         }
52         sort(a,a + cnt);
53         cnt = unique(a,a + cnt) - a;
54         for(int i = 1; i <= cnt; i++)
55         {
56             father[i] = i;
57             r[i] = 0;
58         }
59         int ans = 0;
60         for(int i = 1; i <= m; i++)
61         {
62             int x = Bin(que[i].u);
63             int y = Bin(que[i].v);
64             int fx = find_father(x);
65             int fy = find_father(y);
66             if(fx == fy)
67             {
68                 if(r[x] == r[y] && strcmp(que[i].str,"odd") == 0)
69                     break;
70                 if(r[x] != r[y] && strcmp(que[i].str,"even") == 0)
71                     break;
72                 ans++;
73             }
74             else
75             {
76                 if(strcmp(que[i].str,"odd") == 0)
77                 {
78                     father[fx] = fy;
79                     r[fx] = r[x]^ 1 ^ r[y];
80                 }
81                 else
82                 {
83                     father[fy] = fx;
84                     r[fy] = r[x] ^ r[y] ^ 0;
85                 }
86                 ans ++;
87             }
88         }
89         printf("%d\n",ans);
90     }
91 
92 
93 
94     return 0;
95 }