[HNOI2008]神奇的国度
题解:
MCS算法.详细说明请见cdq的论文--弦图和区间图.
1 #include<iostream> 2 #include<cstdlib> 3 #include<cstdio> 4 #include<cmath> 5 #include<algorithm> 6 #include<cstring> 7 #include<queue> 8 #include<vector> 9 #include<stack> 10 #define MAXN 1000010 11 #define RG register 12 #define LL long long int 13 using namespace std; 14 const int INF=1e9; 15 const int mod=31011; 16 struct node{ 17 int next; 18 int to; 19 }t[MAXN*2]; 20 int head[MAXN*2],num; 21 int n,m; 22 int ans; 23 int du[MAXN],vis[MAXN],q[MAXN]; 24 int col[MAXN],used[MAXN]; 25 void add(int from,int to) 26 { 27 t[++num].next=head[from]; 28 t[num].to=to; 29 head[from]=num; 30 } 31 int main() 32 { 33 freopen("1.in","r",stdin); 34 scanf("%d%d",&n,&m);int x,y; 35 for(int i=1;i<=m;i++){ 36 scanf("%d%d",&x,&y);add(x,y);add(y,x); 37 } 38 for(int i=n;i>=1;i--){ 39 int p=0; 40 for(int j=1;j<=n;j++) if(!vis[j] && du[j]>=du[p]) p=j; 41 q[i]=p;vis[p]=1; 42 for(int j=head[p];j;j=t[j].next) du[t[j].to]++; 43 } 44 for(int i=n;i>=1;i--){ 45 int p=q[i]; 46 for(int j=head[p];j;j=t[j].next) used[col[t[j].to]]=p; 47 int j; 48 for(j=1;;j++) if(used[j]!=p) break; 49 col[p]=j;if(j>ans) ans=j; 50 } 51 printf("%d\n",ans); 52 return 0; 53 }
