1 #include<stdio.h>
2 #include<string.h>
3 #include<vector>
4 #define N 20010
5 using namespace std;
6 int dfn[N];
7 int low[N];
8 int instack[N];
9 int stack[N];
10 int belong[N];
11 int in[N];
12 int out[N];
13 int visnum;
14 int cnt;
15 int stop;
16
17 int n,m;
18 vector<int>node[N];
19 void tarjan(int x)
20 {
21
22
23 dfn[x]=low[x]=++visnum;
24 instack[x]=1;
25 stack[++stop]=x;
26 int j;
27 for(int i=0;i<node[x].size();i++)
28 {
29
30
31 j=node[x][i];
32 if(dfn[j]==0)
33 {
34 tarjan(j);
35 if(low[x]>low[j])
36 low[x]=low[j];
37 }
38 else if(instack[j]==1&&low[x]>dfn[j])
39 low[x]=dfn[j];
40
41
42 }
43
44 if(dfn[x]==low[x])
45 {
46
47
48 cnt++;
49 do
50 {
51 j=stack[stop--];
52 belong[j]=cnt;
53 instack[j]=0;
54 }while(x!=j);
55
56 }
57
58 }
59 int maxa(int x,int y)
60 {
61
62
63 int s;
64 if(x>y) s=x;
65 else s=y;
66 return s;
67 }
68 void init()
69 {
70
71
72 memset(dfn,0,sizeof(dfn));
73 memset(low,0,sizeof(low));
74 memset(instack,0,sizeof(instack));
75 memset(node,0,sizeof(node));
76 memset(in,0,sizeof(in));
77 memset(out,0,sizeof(out));
78 visnum=0;
79 cnt=0;
80 stop=0;
81 }
82 int main()
83 {
84
85
86 int a,b;
87 int i,j;
88 int t;
89 scanf("%d",&t);
90 while(t--){
91 scanf("%d%d",&n,&m);
92 if(m==0)
93 {
94
95
96 printf("%d\n",n);
97 continue;
98 }
99
100
101
102
103 init();
104 for(i=0;i<m;i++)
105 {
106
107
108 scanf("%d%d",&a,&b);
109 node[a].push_back(b);
110
111 }
112
113 for(i=1;i<=n;i++)
114 {
115
116
117 if(dfn[i]==0)
118 tarjan(i);
119 }
120 int s,e;
121 if(cnt==1) printf("0\n");
122 else
123 {
124
125
126 for(i=1;i<=n;i++)
127 for(j=0;j<node[i].size();j++)
128 {
129
130
131 s=belong[i];
132 e=belong[node[i][j]];
133 if(s!=e)
134 {
135
136
137 in[e]=1;
138 out[s]=1;
139 }
140 }
141 int x=0;
142 int y=0;
143
144
145
146
147 for(i=1;i<=cnt;i++)
148 {
149
150
151 if(!in[i])
152 x++;
153 if(!out[i])
154 y++;
155 }
156
157 printf("%d\n",maxa(x,y));
158 }
159 }
160
161 }
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