面试题3：数组中重复的数字

lis = [2,1,3,4,3]
def f(lis):
    for index in range(len(lis)):
        while index != lis[index]:
            if lis[index] == lis[lis[index]]:
                print(lis[index])
                break
            k = lis[index]
            lis[index] = lis[lis[index]]
            lis[k] = k

print(f(lis))

题目二：不修改数组找出重复数字

def f_2(lis):
    if lis == None:
        return False
    end = len(lis) - 1
    start = 1
    while end >= start:
        mid = (end-start)//2+start
        count = contrange(lis, start, mid)
        if end == start:
            if count >1:
                return start
            else:
                break
        if count >(mid - start +1):
            end = mid
        else:
            start = mid + 1

def contrange(lis, start, end):
    if lis == None:
        return False
    c = 0
    for i in range(len(lis)):
        if (lis[i] >= start) and (lis[i] <= end):
            c += 1
    return c