[Link] https://www.acmicpc.net/problem/1197
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import java.util.*;
import java.io.*;
public class Main {
static BufferedReader br;
static int[] seg;
static int[] orig;
public static void main(String[] args) throws IOException {
br = new BufferedReader(new InputStreamReader(System.in));
StringBuilder sb = new StringBuilder();
int[] arr = getArr();
ArrayList<Edge> edges = new ArrayList<>();
PriorityQueue<Edge> pq = new PriorityQueue<>((l, r) -> l.val - r.val);
int v = arr[0], e = arr[1];
for(int i = 0; i < e; i++) {
arr = getArr();
int a = arr[0] - 1, b = arr[1] - 1, c = arr[2];
if(a > b) {
int tmp = a;
a = b;
b = a;
}
pq.add(new Edge(a, b, c));
}
int ans = 0;
int[] parents = new int[v];
for(int i = 0; i < v; i++) parents[i] = i;
while(!pq.isEmpty()) {
Edge cur = pq.poll();
int p1 = getParent(parents, cur.v1);
int p2 = getParent(parents, cur.v2);
if(p1 == p2) continue;
if(p1 < p2) parents[p2] = p1;
else parents[p1] = p2;
ans += cur.val;
}
print(ans);
}
static int getParent(int[] arr, int idx) {
if(idx == arr[idx]) return idx;
else return arr[idx] = getParent(arr, arr[idx]);
}
static class Edge {
int v1;
int v2;
int val;
public Edge(int v1, int v2, int val) { this.v1 = v1; this.v2 = v2; this.val = val; }
}
static int toi(String s) { return Integer.parseInt(s); }
static String[] getLine() throws IOException { return br.readLine().split(" "); }
static int[] getArr() throws IOException { return Arrays.stream(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray(); }
static <T> void print(T s) { System.out.print(s); }
static <T> void println(T s) { System.out.println(s); }
}