344. Reverse String
Please write a function whose function is to reverse the input string.
Example:
Input: s = "hello" Return: "olleh"
class Solution:
def reverseString(self, s):
"""
:type s: str
:rtype: str
"""
#[start:end:step]step default=1
return s[::-1]
7.
Reverse
Integers
Given a 32-bit signed integer, invert the numbers in the integer.
Example 1:
Input: 123 Output: 321
Example 2:
Input: -123 Output: -321
Example 3:
Input: 120 Output: 21
Notice:
Suppose that our environment can only store 32-bit signed integers in the range [−2 31 , 2 31 − 1]. According to this assumption, if the inverted integer overflows, 0 is returned.
class Solution:
def reverse(self, x):
"""
:type x: int
:rtype: int
"""
if x < 0:
r = int(str(x*-1)[::-1]) * -1
elif x < 10:
return x
else:
r = int(str(x)[::-1])
if r > 2**31 - 1 or r < -2**31:
r = 0
return r
387. The first unique character in a string
Given a string, find its first unique character and return its index. Returns -1 if not present.
Case:
s = "leetcode" returns 0. s = "loveleetcode", Return to 2.
Note: You can assume that the string contains only lowercase letters.
class Solution:
def firstUniqChar(self, s):
"""
:type s: str
:rtype: int
"""
from collections import Counter
c1 = Counter(s)
a = list()
for i in c1.keys():
if c1[i] == 1:
a.append(s.index(i))
if len(a) == 0:
return -1
else :
return min(a)
class Solution:
def firstUniqChar(self, s):
"""
:type s: str
:rtype: int
"""
#When the index list is empty, it returns -1, if it is not empty, it returns the minimum value of the index list
import string
return min([s.index(ch) for ch in string.ascii_lowercase if s.count(ch) == 1] or [-1])