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June 25, 2017 02:01
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#include <bits/stdc++.h> | |
using namespace std; | |
#define FOR(i, j, k) for(int i = j; i < k; ++i) | |
#define rep(i, j) FOR(i, 0, j) | |
#define FORr(i, j, k) for(int i = j; i >= k; --i) | |
#define repr(i, j) FOR(i, j, 0) | |
#define INF (1 << 30) | |
typedef long long ll; | |
typedef unsigned long long ull; | |
typedef pair<int, int> P; | |
typedef pair<P, int> Pi; | |
const int MOD = 1e9 + 7; | |
const int dy[]={0, 0, 1, -1}; | |
const int dx[]={1, -1, 0, 0}; | |
template <class T> void chmin(T& a, const T& b) { a = min(a, b); } | |
template <class T> void chmax(T& a, const T& b) { a = max(a, b); } | |
struct edge { int u, v, cost; }; | |
bool comp(const edge& e1, const edge& e2) { | |
return e1.cost < e2.cost; | |
} | |
int N; | |
vector<P> vx, vy; | |
vector<edge> es; | |
int par[100001], rk[100001]; | |
ll res = 0; | |
void init(int n) { | |
rep(i, n) { | |
par[i] = i; | |
rk[i] = 0; | |
} | |
} | |
int find(int x) { | |
if(par[x] == x) return x; | |
else return par[x] = find(par[x]); | |
} | |
void unite(int x, int y) { | |
x = find(x); | |
y = find(y); | |
if(x == y) return; | |
if(rk[x] < rk[y]) par[x] = y; | |
else par[y] = x; | |
if(rk[x] == rk[y]) ++rk[x]; | |
} | |
bool same(int x, int y) { | |
return find(x) == find(y); | |
} | |
void kruskal() { | |
sort(es.begin(), es.end(), comp); | |
init(N); | |
rep(i, es.size()) { | |
edge e = es[i]; | |
if(!same(e.u, e.v)) { | |
unite(e.u, e.v); | |
res += e.cost; | |
} | |
} | |
} | |
int main() { | |
scanf("%d", &N); | |
rep(i, N) { | |
int X, Y; | |
scanf("%d %d", &X, &Y); | |
vx.push_back(P(X, i)); vy.push_back(P(Y, i)); | |
} | |
sort(vx.begin(), vx.end()); sort(vy.begin(), vy.end()); | |
FOR(i, 1, vx.size()) { | |
es.push_back({vx[i - 1].second, vx[i].second, vx[i].first - vx[i - 1].first}); | |
} | |
FOR(i, 1, vy.size()) { | |
es.push_back({vy[i - 1].second, vy[i].second, vy[i].first - vy[i - 1].first}); | |
} | |
kruskal(); | |
printf("%lld\n", res); | |
return 0; | |
} |
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