a121: 質數又來囉

百千.IOhttp://zerojudge.tw/ShowProblem?problemid=a121

• MAX=10000
• is_prime=[False,False]+[True]*(MAX-1)
• primes=[]
• now=2
• while True:
• primes.append(now)
• for i in range(now*2,MAX+1,now):
• is_prime[i]=False
• now+=1
• try:
• while is_prime[now]==False:
• now+=1
• except:
• break
• while True:
• try:
• a,b=input().split()
• a,b=int(a),int(b)
• count=0
• for x in range(a,b+1):
• if x<=MAX:
• if x in primes:
• count+=1
• else:
• for prime in primes:
• if x%prime==0:
• break
• else: # a loop’s else clause runs when no break occurs
• count+=1
• print(count)
• except:
• break