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Commit ddfc8e5

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author
hj.tian
committed
feat: add leetcode75 day29
feat: add leetcode75 day29
1 parent 4ee7fc6 commit ddfc8e5

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3 files changed

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3 files changed

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‎leetcode75/day29_16.py

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from typing import List
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class Solution:
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def threeSumClosest(self, nums: List[int], target: int) -> int:
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"""
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1. i,j,k 暴力破解
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2. 双指针
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-4, -1, 1, 2
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i s-> <-e
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=, return
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>, s+1
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<, e-1
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><需要考虑记录最接近的值(N*N)
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"""
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lens = len(nums)
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if lens < 3:
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raise KeyError
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nums.sort()
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ans = 0
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diff_mins = 100000
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for i in range(lens - 2):
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start = i + 1
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end = lens - 1
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while start < end:
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three_sum = nums[i] + nums[start] + nums[end]
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if three_sum == target:
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return target
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else:
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if three_sum < target:
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start += 1
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else:
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end -= 1
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diff = abs(three_sum - target)
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if diff < diff_mins:
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diff_mins = diff
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ans = three_sum
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return ans
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if __name__ == "__main__":
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assert Solution().threeSumClosest(nums=[-1, 2, 1, -4], target=1) == 2
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assert Solution().threeSumClosest(nums=[0, 0, 0], target=1) == 0

‎leetcode75/day29_3.py

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from collections import Counter
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class Solution:
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def lengthOfLongestSubstring(self, s: str) -> int:
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"""滑动窗口
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s s s s s s
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pwwkew pwwkew pwwkew pwwkew pwwkew pwwkew
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e e e e e e
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max 1 2 1 2 3 3
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=> 3
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"""
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maxs = start = end = 0
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counter = Counter()
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while end < len(s):
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if counter[s[end]] <= 0:
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counter[s[end]] += 1
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else:
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while s[start] != s[end]:
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counter[s[start]] -= 1
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start += 1
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start += 1
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maxs = max(maxs, end - start + 1)
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end += 1
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return maxs
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if __name__ == "__main__":
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assert Solution().lengthOfLongestSubstring("abcabcbb") == 3
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assert Solution().lengthOfLongestSubstring("bbbb") == 1
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assert Solution().lengthOfLongestSubstring("pwwkew") == 3
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assert Solution().lengthOfLongestSubstring("tmmzuxt") == 5

‎leetcode75/day29_76.py

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from collections import Counter
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class Solution:
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def minWindow(self, s: str, t: str) -> str:
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"""
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3. 优化双指针
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s
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ABCBAC, ABC
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e
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"""
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target = Counter(t)
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record = Counter()
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source = [(char, index) for index, char in enumerate(s) if char in t]
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min_start, min_end = 0, len(s) + 1
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start = end = 0
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while end < len(source) and start + len(t) <= len(source):
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record[source[end][0]] += 1
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# 满足了条件,覆盖全部t的位置
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if record >= target:
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# 移动 start, 直到不满点
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while record >= target:
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record[source[start][0]] -= 1
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start += 1
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if source[end][1] - source[start - 1][1] < min_end - min_start:
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min_start, min_end = source[start - 1][1], source[end][1]
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end += 1
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if min_end == len(s) + 1:
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return ""
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return s[min_start : min_end + 1]
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# class Solution:
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# def minWindow(self, s: str, t: str) -> str:
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# """
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# 2. 双指针
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# s
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# ADOBECODEBANC
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# e
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# s
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# ADOBECODEBANC # e走到覆盖全部t的位置
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# e
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# s
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# ADOBECODEBANC # s走到不覆盖全部t的位置, 计算长度并更新最小长度
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# e
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# s s
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# ADOBECODEBANC -> ADOBECODEBANC
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# e e
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# (0,5) -> (5, 10) -> (9, 12)
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# => s[9:12+1]
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# """
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# target = Counter(t)
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# record = Counter()
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# min_start, min_end = 0, len(s) + 1
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# start = end = 0
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# while end < len(s) and start + len(t) <= len(s):
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# if s[end] in t:
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# record[s[end]] += 1
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# # 满足了条件,覆盖全部t的位置
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# if all(record[char] >= target[char] for char in target):
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# # 移动 start, 直到不满点
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# while all(record[char] >= target[char] for char in target):
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# record[s[start]] -= 1
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# start += 1
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# if end - (start - 1) < min_end - min_start:
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# min_start, min_end = start - 1, end
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# end += 1
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# if min_end == len(s) + 1:
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# return ""
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# return s[min_start : min_end + 1]
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# class Solution:
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# def minWindow(self, s: str, t: str) -> str:
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# """
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# 1. 暴力枚举
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# a. 找到起始点,只要字母在t中都可以成为起始点
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# b. 往右走,直到覆盖t, 更新最小长度
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# """
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# # 构建起始点
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# starts = []
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# for i in range(len(s)):
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# if s[i] in t and i + len(t) <= len(s):
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# starts.append(i)
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# mins = len(s) + 1
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# mins_start = mins_end = 0
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# flag = False
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# for start in starts:
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# end = start
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# target = Counter(t)
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# record = Counter()
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# while end < len(s):
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# if s[end] in t:
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# record[s[end]] += 1
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# if all(record[char] >= target[char] for char in target.keys()) and end - start + 1 < mins:
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# # 记录搜索到了,更新最小长度
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# mins = end - start + 1
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# mins_start, mins_end = start, end
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# flag = True
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# break
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# end += 1
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# if flag is False:
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# return ""
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# return s[mins_start : mins_end + 1]
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if __name__ == "__main__":
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assert Solution().minWindow(s="ADOBECODEBANC", t="ABC") == "BANC"
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assert Solution().minWindow(s="a", t="a") == "a"
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assert Solution().minWindow(s="a", t="aa") == ""
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assert Solution().minWindow(s="a", t="b") == ""

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