BZOJ1854 [Scoi2010]游戏

 1 //It is made by ljh2000
 2 #include <iostream>
 3 #include <cstdlib>
 4 #include <cstring>
 5 #include <cstdio>
 6 #include <cmath>
 7 #include <algorithm>
 8 #include <ctime>
 9 #include <vector>
10 #include <queue>
11 #include <map>
12 #include <set>
13 using namespace std;
14 typedef long long LL;
15 const int MAXN = 10011;
16 int n,father[MAXN];
17 bool ok[MAXN];
18 
19 inline int getint()
20 {
21     int w=0,q=0; char c=getchar();
22     while((c<‘0‘ || c>‘9‘) && c!=‘-‘) c=getchar(); if(c==‘-‘) q=1,c=getchar(); 
23     while (c>=‘0‘ && c<=‘9‘) w=w*10+c-‘0‘, c=getchar(); return q ? -w : w;
24 }
25 inline int find(int x){ if(father[x]!=x) father[x]=find(father[x]); return father[x]; }
26 inline void work(){
27     n=getint(); for(int i=1;i<=10001;i++) father[i]=i; int x,y,r1,r2;
28     for(int i=1;i<=n;i++) {
29     x=getint(); y=getint(); r1=find(x); r2=find(y);
30     if(r1==r2) ok[r1]=true;
31     else{
32         if(r1>r2) swap(r1,r2);
33         if(!ok[r1]) ok[r1]=true; else ok[r2]=true;
34         father[r1]=r2;
35     }
36     }
37     for(int i=1;i<=10001;i++) if(!ok[i]) { printf("%d",i-1); return ; }
38     printf("10000");
39 }
40 
41 int main()
42 {
43     work();
44     return 0;
45 }