longestCommonPrefix

這是leetcode中關於list中元素最長公共前綴查找算法，這其中要注意空元素的處理以及最終最長前綴的輸出方式

s = input()
if len(s) == 0:
    print("no marching!")
else:
    s = s.split(',')
    b = []
    len_all = len(s)
    len_next = len(s[0])
    i = 1
    while i < len_all:
        len_next = min(len(s[i]),len_next)
        i = i+ 1
    x = 0
    while x < len_next:
        sign = 0
        i = 0
        while i < (len_all - 1):
            if s[i][x] == s[i+1][x]:
                i = i + 1
            else:
                sign = 1
                break
        if sign == 0:
            b.append(s[0][x])
        else:
            break
        x = x + 1
    if b:
        print("".join(b))
    #     以空格爲界限輸出list b
    else:
        print("no marching")