考えたこと
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<ll> VL;
typedef vector<VL> VVL;
typedef pair<int, int> PII;
#define FOR(i, a, n) for (ll i = (ll)a; i < (ll)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()
#define IN(a, b, x) (a<=x&&x<b)
#define MP make_pair
#define PB push_back
const int INF = (1LL<<30);
const ll LLINF = (1LL<<60);
const double PI = 3.14159265359;
const double EPS = 1e-12;
const int MOD = 1000000007;
template <typename T> T &chmin(T &a, const T &b) { return a = min(a, b); }
template <typename T> T &chmax(T &a, const T &b) { return a = max(a, b); }
int dx[] = {0, 1, 0, -1}, dy[] = {1, 0, -1, 0};
class UnionFind {
public:
const static int MAX_N = 205;
int par[MAX_N];
int rank[MAX_N];
int s[MAX_N];
bool used[MAX_N];
UnionFind() { init(); }
UnionFind(int n) { init(n); }
void init() { for(int i=0; i<MAX_N; ++i) par[i] = i, rank[i] = 0, s[i] = 1; }
void init(int n) { for(int i=0; i<n; ++i) par[i] = i, rank[i] = 0, s[i] = 1; }
int find(int x) {
if(par[x] == x) return x;
return par[x] = find(par[x]);
}
void unite(int x, int y) {
x = find(x);
y = find(y);
if(x == y) return;
if(rank[x] < rank[y]) {
par[x] = y; s[y] = s[x] + s[y];
} else {
par[y] = x; s[x] = s[x] + s[y];
if( rank[x] == rank[y] ) rank[x]++;
}
}
int size(int x) { return s[find(x)];}
bool same(int x, int y) { return find(x) == find(y);}
int group(int n) {
REP(i, n) used[find(i)] = true;
int ret = 0;
REP(i, n) if(used[i]) ret++;
return ret;
}
};
UnionFind uf;
VVI es;
class ChristmasTreeDecoration {
public:
int solve(vector <int> col, vector <int> x, vector <int> y)
{
uf.init();
es.clear();
int n = col.size(), m = x.size();
REP(i, m) {
x[i]--, y[i]--;
if(col[x[i]] == col[y[i]]) {
es.PB({1, x[i], y[i]});
} else {
es.PB({0, x[i], y[i]});
}
}
sort(ALL(es));
int ret = 0;
REP(i, m) {
if(!uf.same(es[i][1], es[i][2])) {
uf.unite(es[i][1], es[i][2]);
ret += es[i][0];
}
}
return ret;
}
};