开学了,不能愉快地刷题了QAQ

差分约束(以前用并查集做真是作死。。)然后有个点比较坑,要过的话就要倒着加边,否则TLE

 1 #include<bits/stdc++.h>
 2 #define inc(i,l,r) for(int i=l;i<=r;i++)
 3 #define dec(i,l,r) for(int i=l;i>=r;i--)
 4 #define link(x) for(edge *j=h[x];j;j=j->next)
 5 #define mem(a) memset(a,0,sizeof(a))
 6 #define inf 1e9
 7 #define ll long long
 8 #define succ(x) (1<<x)
 9 #define lowbit(x) (x&(-x))
10 #define NM 200000+5
11 using namespace std;
12 int read(){
13     int x=0,f=1;char ch=getchar();
14     while(!isdigit(ch)){if(ch=='-')f=-1;ch=getchar();}
15     while(isdigit(ch))x=x*10+ch-'0',ch=getchar();
16     return x*f;
17 }
18 struct edge{
19     int t,v;
20     edge *next;
21 }e[2*NM],*h[NM],*o=e;
22 void add(int x,int y,int v){
23     o->t=y;o->v=v;o->next=h[x];h[x]=o++;
24 }
25 int n,m,_x,_y,_t,d[NM],cnt[NM];
26 ll s;
27 bool v[NM];
28 queue<int >q;
29 bool spfa(){
30     v[0]++;q.push(0);
31     while(!q.empty()){
32         int t=q.front();q.pop();v[t]=false;
33         if(cnt[t]>=n)return 0;
34         link(t)if(d[j->t]<d[t]+j->v){
35             d[j->t]=d[t]+j->v;
36             if(++cnt[j->t]>=n)return 0;
37             if(!v[j->t])v[j->t]++,q.push(j->t);
38         }
39     }
40     return 1;
41 }
42 int main(){
43     n=read();m=read();
44     while(m--){
45         _t=read();_x=read();_y=read();
46         if(_t==1)add(_x,_y,0),add(_y,_x,0);
47         else if(_t==2)add(_x,_y,1);
48         else if(_t==3)add(_y,_x,0);
49         else if(_t==4)add(_y,_x,1);
50         else add(_x,_y,0);
51         if((_t==2||_t==4)&&_x==_y){
52             printf("-1\n");return 0;
53         }
54     }
55     dec(i,n,1)add(0,i,1);
56     if(!spfa()){
57         printf("-1\n");return 0;
58     }
59 //    inc(i,1,n)printf("%d ",d[i]);putchar('\n');
60     inc(i,1,n)s+=d[i];
61     printf("%lld\n",s);
62     return 0;
63 }
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posted on 2016-02-21 17:22  onlyRP  阅读(181)  评论(0编辑  收藏  举报