Interesting Computer Game

Interesting Computer Game

#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <set>
#include <queue>
#include <map>
#include <sstream>
#include <cstdio>
#include <cstring>
#include <numeric>
#include <cmath>
#include <iomanip>
#include <deque>
#include <bitset>
#include <cassert>
//#include <unordered_set>
#include <unordered_map>
#define ll              long long
#define pii             pair<int, int>
#define rep(i,a,b)      for(int  i=a;i<=b;i++)
#define dec(i,a,b)      for(int  i=a;i>=b;i--)
#define forn(i, n)      for(int i = 0; i < int(n); i++)
using namespace std;
int dir[4][2] = { { 1,0 },{ 0,1 } ,{ 0,-1 },{ -1,0 } };
const long long INF = 0x7f7f7f7f7f7f7f7f;
const int inf = 0x3f3f3f3f;
const double pi = acos(-1.0);
const double eps = 1e-6;
const int mod = 1e9 + 7;

inline ll read()
{
    ll x = 0; bool f = true; char c = getchar();
    while (c < '0' || c > '9') { if (c == '-') f = false; c = getchar(); }
    while (c >= '0' && c <= '9') x = (x << 1) + (x << 3) + (c ^ 48), c = getchar();
    return f ? x : -x;
}
inline ll gcd(ll m, ll n)
{
    return n == 0 ? m : gcd(n, m % n);
}
void exgcd(ll A, ll B, ll& x, ll& y)
{
    if (B) exgcd(B, A % B, y, x), y -= A / B * x; else x = 1, y = 0;
}
inline int qpow(int x, ll n) {
    int r = 1;
    while (n > 0) {
        if (n & 1) r = 1ll * r * x % mod;
        n >>= 1; x = 1ll * x * x % mod;
    }
    return r;
}
inline int inv(int x) {
    return qpow(x, mod - 2);
}
ll lcm(ll a, ll b)
{
    return a * b / gcd(a, b);
}
/**********************************************************/
const int N = 1e5 + 5;

unordered_map<int, int> f, vis,p,cntdot;
int find(int x) {
    return f[x] == x ? x : f[x] = find(f[x]);
}
bool add(int x, int y) {
    int fx = find(x), fy = find(y);
    if (fx != fy) {
        f[fx] = fy;
        return true;
    }
    return false;
}

int cnt, fg, sz;

int a[N], b[N],c[N];
int main() {
    //ios::sync_with_stdio(false);cin.tie(0); cout.tie(0);
    int T;
    scanf("%d", &T);
    int cntt = 1;
    while (T--)
    {
        memset(c, 0, sizeof(c));
        vis.clear();
        f.clear();
        cntdot.clear();
        p.clear();
        int res = 0;
        cnt = 0;
        int n;
        scanf("%d", &n);
        rep(i, 1, n)
        {
            scanf("%d%d", &a[i], &b[i]);
            f[a[i]] = a[i];
            f[b[i]] = b[i];
        }
        int cntg = 0, cntn = 0, len = 1;
        unordered_map<int, int> mmp;
        rep(i, 1, n)
        {
            if (find(a[i]) == find(b[i]))
                c[len++] = find(a[i]);
            else
                add(a[i], b[i]);
        }
        rep(i, 1, len)
            p[find(c[i])] = 1;
        rep(i, 1, n)
        {
            if (!vis[a[i]])
                cntdot[find(a[i])]++;
            vis[a[i]] = 1;
            if (!vis[b[i]])
                cntdot[find(b[i])]++;
            vis[b[i]] = 1;
        }
        for (auto x : cntdot)
        {
            if (!p[x.first])
                res--;
            res += x.second;
        }
        printf("Case #%d: %d\n", cntt++,res);
    }
}