PAT-B 1012. 数字分类(python)

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1. py中初始数组，a1=a2=a3=a4=a5=[], 这样a1,a2,a3,a4,a5是指向同一个链表的引用。这和C不一样的。

2. round(number, significant)可以用来四舍五入小数

3. 暂未发现built-in中有average函数，用的是float(sum(a4)) / len(a4)

源码：

if __name__ == "__main__" :    # initialize them seperately    a1=[]    a2=[]    a3=[]    a4=[]    a5=[]        num = raw_input().split(' ')    for i in range(int(num[0])) :        now = int(num[i+1])        if now%10==0 :            a1.append(now)        elif now%5==1 :            a2.append(now)        elif now%5==2 :            a3.append(now)        elif now%5==3 :            a4.append(now)        elif now%5==4 :           # cannot use "else" straight, use this contrain            a5.append(now)    if a1==[] :        print "N",    else :        print sum(a1),    if a2==[] :        print "N",    else :        a2_ans=0        for i in range(len(a2)) :            if i%2==0 :                a2_ans = a2_ans + a2[i]            else :                a2_ans = a2_ans - a2[i]        print a2_ans,    if a3==[] :        print "N",    else :        print len(a3),    if a4==[] :        print "N",    else :        print round(float(sum(a4))/len(a4), 1),    if a5==[] :        print "N"    else :        print max(a5)

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