Tunnels

input/code.cpp: In function 'int main(int, const char**)':
input/code.cpp:58:13: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     sd2(n,m);
             ^
input/code.cpp:61:17: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         sd2(a,b);
                 ^

#include<bits/stdc++.h>
#define pb push_back
#define PI acos(-1)
#define mp make_pair
#define fastio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define F first
#define sd(x) scanf("%d",&x)
#define sd2(x,y) scanf("%d%d",&x,&y)
#define sdl(x) scanf("%lld",&x)
#define sd2l(x,y) scanf("%lld%lld",&x,&y)
#define maxn 100010
#define S second
#define ll long long int
#define inf 1000002014
#define infl 1000000000000020000ll
#define mod 1000000007
#define clrs(x) memset(x,0,sizeof x)
#define sz(x) (int) x.size()
#define pi pair< int,int >
#define pii pair<pi,int>
#define pu push
#define ld long double
#define trace1(x)  cerr << #x << ": " << x << endl
#define trace2(x, y)  cerr << #x << ": " << x << " | " << #y << ": " << y << endl
using namespace std;
queue< int > q;
int indeg[maxn];int outdeg[maxn];
vector< pi >v[maxn];
int ans[maxn];
int inq[maxn];
void dfs(int s)
{
    int done1 = 0;
    for (int i = 0; i < sz(v[s]); ++i)
    {
        if(v[s][i].S == 1 || done1)
            continue;
        else
        {
            done1 = 1;
            v[s][i].S = 1;
            outdeg[s]--;
            indeg[v[s][i].F]--;
            if(indeg[v[s][i].F] == 0 && !inq[v[s][i].F])
            {
                q.push(v[s][i].F);
                inq[v[s][i].F] = 1;
            }
            dfs(v[s][i].F);
        }
    }
}
int main(int argc, char const *argv[])
{
    //freopen("input.txt","r",stdin);
    //freopen("output.txt","w",stdout);
    int n,m,a,b;
    sd2(n,m);
    for(int i=0;i<m;i++)
    {
        sd2(a,b);
        v[a].pb(mp(b,0));
        outdeg[a]++;
        indeg[b]++;
    }
    for (int i = 1; i <= n; ++i)
    {
        if(indeg[i]==0 && outdeg[i]!=0)
        {
            q.push(i);
            inq[i] = 1;
        }
    }
    int fans = 0;
    while(!q.empty())
    {
        int to = q.front();
        if(outdeg[to]==0)
        {
            fans+=ans[to];
            q.pop();
        }
        else
        {
            ans[to]++;
            dfs(to);
        }
    }
    printf("%d\n",fans);
    return 0;
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 1

Verdict: ACCEPTED

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: ACCEPTED

Test 5

Group: 1

Verdict: ACCEPTED

Test 6

Group: 2

Verdict: ACCEPTED

Test 7

Group: 2

Verdict: ACCEPTED

Test 8

Group: 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED

Test 11

Group: 3

Verdict: ACCEPTED

Test 12

Group: 3

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: ACCEPTED

Test 14

Group: 3

Verdict: ACCEPTED

Test 15

Group: 3

Verdict: ACCEPTED