python3代码:
写完去看题解发现思路一样写法有点差别
python3 代码
a,b=map(int,input().strip().split())
n=int(input().strip())
l=list(list(map(int,input().strip().split())) for i in range(n))
l.sort()
h=l[0][1]
q=l[0][0]
cs=0
for i in range(1,n):
if l[i][0]<=a and l[i][1]>h:
h=l[i][1]
q=l[i][0]
if l[i][0]>a or l[i][1]>=b:
if q<=a:
cs+=1
a=h
q=l[i][0]
h=l[i][1]
else:
cs=-1
break
if a>=b:
break
if a<b and l[-1][0]<=a and l[-1][1]>=b:
cs+=1
a=b
if a==b and q<=a and h>=a and cs==0:
cs+=1
if a>=b:
print(cs)
else:
print(-1)