1.問題の説明

2.問題分析

3.私の回答

import sys
import heapq

INF = sys.maxsize
n, m = map(int, sys.stdin.readline().rstrip().split())
pq = []
parents = [i for i in range(n+1)]
for _ in range(m):
    a, b, c = map(int, sys.stdin.readline().rstrip().split())
    heapq.heappush(pq, [-c, a, b])

def find(node):
    if parents[node] == node: return node
    else:
        parents[node] = find(parents[node])
        return parents[node]

def union(node1, node2):
    root1, root2 = find(node1), find(node2)
    if root1 == root2: return False
    else:
        parents[root2] = root1
        return True

def Krsukal():
    total = 0
    edge_cnt = 0
    while pq:
        cur_cost, node1, node2 = heapq.heappop(pq)
        if union(node1, node2):
            total -= cur_cost
            edge_cnt += 1
            if edge_cnt == n-1: break
    if edge_cnt == n-1: return total
    else: return -1

ans = Krsukal()
print(ans)