7、整数反转,字符反序输出:
class reverse: def reverse(self,x): if x < (-2**31) or (x > 2**31 -1): return 0 elif x >= 0: return int(str(x)[::-1]) else: return int(str(x)[1:][::-1])*-1
3、无重复的字符子串
class solution: def lengthoflongestSubstring(self,s): st = {} i,ans = 0,0 for j in range(len(s)): if s[j] in st: i = max(st[s[j]],i) ans = max(ans,j-i+1) st[s[j]] = j+1 return ans