URAL-1997 Those are not the droids you're looking for 二分匹配
题目链接：http://acm.timus.ru/problem.aspx?space=1&num=1997
题意：记录了n个人进出门的时间点，每个人在房子里面待的时间要么小于等于a，要么大于等于b，询问能否对进出门的时间点找到一个合适的匹配。
对于满足的要求建立边即可，然后看是否能找到最大匹配。
1 //STATUS:C++_AC_109MS_4361KB 2 #include <functional> 3 #include <algorithm> 4 #include <iostream> 5 //#include <ext/rope> 6 #include <fstream> 7 #include <sstream> 8 #include <iomanip> 9 #include <numeric> 10 #include <cstring> 11 #include <cassert> 12 #include <cstdio> 13 #include <string> 14 #include <vector> 15 #include <bitset> 16 #include <queue> 17 #include <stack> 18 #include <cmath> 19 #include <ctime> 20 #include <list> 21 #include <set> 22 #include <map> 23 using namespace std; 24 //#pragma comment(linker,"/STACK:102400000,102400000") 25 //using namespace __gnu_cxx; 26 //define 27 #define pii pair<int,int> 28 #define mem(a,b) memset(a,b,sizeof(a)) 29 #define lson l,mid,rt<<1 30 #define rson mid+1,r,rt<<1|1 31 #define PI acos(-1.0) 32 //typedef 33 typedef __int64 LL; 34 typedef unsigned __int64 ULL; 35 //const 36 const int N=1010; 37 const int INF=0x3f3f3f3f; 38 const int MOD=95041567,STA=8000010; 39 const LL LNF=1LL<<60; 40 const double EPS=1e-8; 41 const double OO=1e15; 42 const int dx[4]={-1,0,1,0}; 43 const int dy[4]={0,1,0,-1}; 44 const int day[13]={0,31,28,31,30,31,30,31,31,30,31,30,31}; 45 //Daily Use ... 46 inline int sign(double x){return (x>EPS)-(x<-EPS);} 47 template<class T> T gcd(T a,T b){return b?gcd(b,a%b):a;} 48 template<class T> T lcm(T a,T b){return a/gcd(a,b)*b;} 49 template<class T> inline T lcm(T a,T b,T d){return a/d*b;} 50 template<class T> inline T Min(T a,T b){return a<b?a:b;} 51 template<class T> inline T Max(T a,T b){return a>b?a:b;} 52 template<class T> inline T Min(T a,T b,T c){return min(min(a, b),c);} 53 template<class T> inline T Max(T a,T b,T c){return max(max(a, b),c);} 54 template<class T> inline T Min(T a,T b,T c,T d){return min(min(a, b),min(c,d));} 55 template<class T> inline T Max(T a,T b,T c,T d){return max(max(a, b),max(c,d));} 56 //End 57 58 int vis[N],y[N],w[N][N],t[N][2],id[N],l[N],r[N]; 59 int n,a,b,cnt1,cnt2; 60 61 int dfs(int u) 62 { 63 int v; 64 for(v=0;v<cnt1;v++){ 65 if(vis[v] || !w[u][v])continue; 66 vis[v]=1; 67 if(y[v]==-1 || dfs(y[v])){ 68 y[v]=u; 69 return 1; 70 } 71 } 72 return 0; 73 } 74 75 int main() 76 { 77 // freopen("in.txt","r",stdin); 78 int i,j,L,R,ok; 79 while(~scanf("%d%d",&a,&b)) 80 { 81 L=b+1,R=a-1; 82 scanf("%d",&n); 83 cnt1=cnt2=0; 84 for(i=0;i<n;i++){ 85 scanf("%d%d",&t[i][0],&t[i][1]); 86 if(t[i][1]){ 87 l[cnt1]=i; 88 id[i]=cnt1++; 89 } 90 else { 91 r[cnt2]=i; 92 id[i]=cnt2++; 93 } 94 } 95 mem(w,0); 96 for(i=0;i<n;i++){ 97 if(t[i][1]==0)continue; 98 for(j=i-1;j>=0;j--){ 99 if(t[j][1]==1)continue; 100 if(t[i][0]-t[j][0]>=L && t[i][0]-t[j][0]<=R)continue; 101 w[id[i]][id[j]]=1; 102 } 103 } 104 mem(y,-1);ok=1; 105 for(i=0;i<cnt1;i++){ 106 mem(vis,0); 107 if(dfs(i)==0){ 108 ok=0; 109 break; 110 } 111 } 112 113 if(ok){ 114 printf("No reason\n"); 115 for(i=0;i<cnt1;i++){ 116 printf("%d %d\n",t[r[i]][0],t[ l[ y[i] ] ][0]); 117 } 118 } 119 else printf("Liar\n"); 120 121 } 122 return 0; 123 }
