Link:
https://www.hackerrank.com/challenges/even-tree
1 def search(a,b): # 根据核心算法和题目要求要筛选边 2 seen = {} 3 seen[a] = True 4 q = [] 5 6 for x in adj[a]: 7 if x != b: 8 seen[x] = True 9 q.append(x) 10 s = len(q) + 1 11 while q: 12 n = q.pop() 13 for x in adj[n]: 14 if x not in seen: 15 seen[x] = True 16 q.append(x) 17 s += 1 18 return (s+1)%2 19 20 [N,M] = [int(x) for x in raw_input().split(' ')] 21 edges = [] # 保存边的list 22 adj = {} # 保存邻接的dict 23 for a in xrange(1,N+1): # 初始化 24 adj[a] = [] 25 26 for a in xrange(M): 27 [x,y] = [int(z) for z in raw_input().split(' ')] 28 adj[x].append(y) # 保存边的对应，没有方向性 29 adj[y].append(x) 30 edges.append((x,y)) # 保存边边 31 32 count = 0 33 for e in edges: 34 (x,y) = e 35 if search(x,y): #依次查看每个边是否能移开 36 count += 1 37 adj[x].remove(y) 38 adj[y].remove(x) 39 40 print count
学习
图的基本结构
edge, adj建立dict/list保存
然后根据算法进行计算
本质
换了一个数据的结构
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