53.寻宝

'''
n,v = map(int,input().split())
graph = [[10001]*(n+1) for _ in range(n+1)]

# 用邻接矩阵存储各边信息
for i in range(v):
    x,y,z = map(int,input().split())
    graph[x][y] = z
    graph[y][x] = z
visit = [False] *(n+1)
minDist = [10001]*(n+1)

for i in range(1,n+1):
    minval = 10002
    cur = -1
    for j in range(1,n+1): # 找到距离当前节点最近的点
        if visit[j] == False and minDist[j] < minval:
            cur = j
            minval = minDist[j]
    visit[cur] = True
    for k in range(1,n+1): # 把与当前节点相连接的点的距离换成权重值
        if visit[k] == False and graph[cur][k] < minDist[k]:
            minDist[k] = graph[cur][k]
ans = 0
for i in range(2,n+1):
    ans += minDist[i]
print(ans)
'''
father = []

def init(n):
    global father
    father = list(range(n+1))
def find(x):
    if x != father[x]:
        father[x] = find(father[x])
    return father[x]


def join(x,y):
    i = find(x)
    j = find(y)
    if i != j:
        father[j] = i
    

def kruscal(edge,n):
    init(n)
    edge.sort(key = lambda x:x[2])
    res = 0
    for s,e,val in edge:
        finds = find(s)
        finde = find(e)
        if finds != finde:
            res += val
            join(finds,finde)
    return res
if __name__=='__main__':
    n,m = map(int,input().split())
    edge = []
    for i in range(m):
        s,e,val = map(int,input().split())
        edge.append([s,e,val])
    res = kruscal(edge,n)
    print(res)

53. 寻宝（第七期模拟笔试）

两种方法构造最小生成树，Prim，Kruscal方法。