【python】幼儿园分班

题目链接：https://blog.youkuaiyun.com/tec_sun/article/details/99292594

二分着色问题：https://blog.youkuaiyun.com/tec_sun/article/details/99292594

【一些图的基础知识：https://www.cnblogs.com/5poi/p/7466760.html】

1. 首先需要将小朋友的请求转换成graph的格式：

num = int(input())
req = int(input())
graph = [[] for i in range(num)]

for i in range(req):
    lst = list(map(int,input().split(' ')))
    graph[lst[0]-1].append(lst[1]-1)
    graph[lst[1]-1].append(lst[0]-1)

2. 深度优先遍历：

record = [0]*num
def dfs(point,c):
    record[point] = c
    for i in graph[point]:
        if record[i] == c:
            return False
        elif record[i] == -c:
            continue
        elif record[i] == 0 and not dfs(i,-c):
            return False
    return True

flag = 1
for i in range(num):
    if record[i] == 0 and not dfs(i,1):
        flag = 0
        break
print(flag)