支持RC喵，关注RC谢谢喵~

a='';l=0;w='';maxl=0
n=input()
for i in range(len(n)):
    for j in range(i,len(n)):
        if n[j] not in a:
            a=a+n[j]
            l+=1
        else:
            break
    if l>maxl:
        maxl=l;w=a
    l=0;a=''
print(w)

1. d~~~~[

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flag=[False]*26
for k in range(i,j+1):
if flag[ord(s[k])-ord("a")]==False:
flag[ord(s[k])-ord("a")]=True
else:
return False
return True

s=input() maxlen=0 for i in range(0,len(s)): j=i+1 while j<len(s) and pd(i,j)==True: j+=1 if j-i>maxlen: maxlen=j-i pos=i print(s[pos:pos+maxlen])

def pd(i,j):    #判断[i,j]范围内的子串是否包含重复字符
    flag=[False]*26
    for k in range(i,j+1):
        if flag[ord(s[k])-ord("a")]==False:
            flag[ord(s[k])-ord("a")]=True
        else:
            return False
    return True

s=input()
maxlen=0   #记录最长不重复子串的长度
for i in range(0,len(s)):
    j=i+1
    while j<len(s) and pd(i,j)==True:
        j+=1
    if j-i>maxlen:    #判断是否找到更长的不重复子串
        maxlen=j-i
        pos=i
print(s[pos:pos+maxlen])

Python的哦~

x=input()
s=""
s1=""
for i in range(len(x)):
    for j in range(i,len(x)):
        if x[j] not in s1:
            s1+=x[j]
            if len(s1)>len(s):
                s=s1
        else:
            s1=""
            break
print(s)        

好久没打代码了 太菜了w

s=input()
a=[0]*26
ans=''
cnt=''
for i in s:
    if a[ord(i)-ord('a')]==0:
        a[ord(i)-ord('a')]+=1
        cnt+=i
    else:
        if len(cnt)>len(ans):
            ans=cnt
        cnt=''
        for j in range(26):
            a[j]=0
        a[ord(i)-ord('a')]+=1
        cnt+=i
if len(cnt)>len(ans):
    ans=cnt
print(ans)

s=input() maxlen=0 for i in range(0,len(s)): j=i+1 while j<len(s) and pd(i,j)==True: j+=1 if j-i>maxlen: maxlen=j-i pos=i print(s[pos:pos+maxlen])