6장 4번 ~ 7장 2번

6장 4번

• 나의 풀이

  class Solution:
    def mostCommonWord(self, paragraph: str, banned: List[str]) -> str:
        wordCount = {}
        for word in paragraph.lower().split():
            word = word.strip(',.')
            wordCount[word] = wordCount.get(word,0)+1
        new = sorted(wordCount.items(),key = lambda x : x[1])
        del new[-1]
        return new[-1][0]

주의:input=['a.']일때는 안됨.

• 답지 풀이

class Solution:
    def mostCommonWord(self, paragraph: str, banned: List[str]) -> str:
        words = [word for word in re.sub(r'[^\w]',' ',paragraph)
                .lower().split()
                        if word not in banned]
        counts = collections.Counter(words)
        return counts.most_common(1)[0][0]

6장 5번

• 나의 풀이
• list = [] for str in strs: list = sorted(str) ???
• 답지 풀이
• class Solution: def groupAnagrams(self, strs: List[str]) -> List[List[str]]: anagrams = collections.defaultdict(list) for word in strs: anagrams[''.join(sorted(word))].append(word) return anagrams.values()

6장 6번

• 답지 풀이

  class Solution:
    def longestPalindrome(self, s: str) -> str:
        def expand(left:int, right:int) ->str:
            while left >=0 and right <=len(s) and s[left] == s[right-1]:
                left -=1
                right +=1
            return s[left + 1: right -1]
  
  

    if len(s)<2 or s == s[::-1]:
        return s

    result = ''

    for i in range(len(s)-1):
        result = max(result,
                    expand(i, i+1),
                    expand(i,i+2),
                     key = len
                    )

    return result

## 7장 7번

* 답지 풀이

class Solution:
def twoSum(self, nums: List[int], target: int) -> List[int]:
for i in range(len(nums)):
for j in range(i+1,len(nums)):
if nums[i] + nums[j] ==target:
return [i,j]

## 7장 8번
left <= right일때 빗물이 고인다.? x
* 답지 풀이

class Solution:
def trap(self, height: List[int]) -> int:
if not height:
return 0

    volume = 0
    left,right = 0 , len(height) - 1
    left_max , right_max = height[left],height[right]

    while left<right:
        left_max,right_max = max(height[left],left_max),max(height[right],right_max)
        if left_max <= right_max:
            volume += left_max - height[left]
            left +=1
        else:
            volume += right_max - height[right]
            right-=1
        return volume

```