add classic150

Author: Navy.Tian

classic150/_001_88.py

@@ -0,0 +1,44 @@
+# https://leetcode.cn/problems/merge-sorted-array/?envType=study-plan-v2&id=top-interview-150
+
+from typing import List
+
+
+class Solution:
+    def merge(self, nums1: List[int], m: int, nums2: List[int], n: int) -> None:
+        """
+        Do not return anything, modify nums1 in-place instead.
+        """
+        # 从后往前, 较大的移动到后面，并移动该索引不断向前
+        start = m + n - 1
+        while start >= 0 and m > 0 and n > 0:
+            if nums1[m - 1] > nums2[n - 1]:
+                nums1[start] = nums1[m - 1]
+                m -= 1
+            else:
+                nums1[start] = nums2[n - 1]
+                n -= 1
+            start -= 1
+
+        # m有多余不需要考虑，不需要移动，所以只需要考虑移动剩余的n到 nums1
+        while start >= 0 and n > 0:
+            nums1[start] = nums2[n - 1]
+            n -= 1
+            start -= 1
+
+
+if __name__ == "__main__":
+    nums1 = [1, 2, 3, 0, 0, 0]
+    Solution().merge(nums1=nums1, m=3, nums2=[2, 5, 6], n=3)
+    assert nums1 == [1, 2, 2, 3, 5, 6]
+
+    nums1 = [1]
+    Solution().merge(nums1=nums1, m=1, nums2=[], n=0)
+    assert nums1 == [1]
+
+    nums1 = [0]
+    Solution().merge(nums1=nums1, m=0, nums2=[1], n=1)
+    assert nums1 == [1]
+
+    nums1 = [1, 2, 3, 0]
+    Solution().merge(nums1=nums1, m=3, nums2=[0], n=1)
+    assert nums1 == [0, 1, 2, 3]

classic150/_002_27.py

@@ -0,0 +1,52 @@
+# https://leetcode.cn/problems/remove-element/?envType=study-plan-v2&id=top-interview-150
+from typing import List
+
+
+class Solution:
+    def removeElement(self, nums: List[int], val: int) -> int:
+        start, end = 0, len(nums)
+        total = 0
+        while start < end:
+            # <---------------|---->
+            #           找到可以替换的 end, 并往后走一步，记录+1
+            while end > start:
+                if nums[end - 1] == val:
+                    end -= 1
+                    total += 1
+                else:
+                    break
+            # <-----|----------|---->
+            #   找到可以替换的 start
+            # 交换 start, end, 并均往前往后走一步, 记录+1
+            while start < end:
+                if nums[start] == val:
+                    nums[start], nums[end - 1] = nums[end - 1], nums[start]
+                    end -= 1
+                    start += 1
+                    total += 1
+                    break
+                start += 1
+        # 返回总长度 - 记录值，为新长度
+        return len(nums) - total
+
+
+if __name__ == "__main__":
+    nums = [1]
+    assert Solution().removeElement(nums=nums, val=1) == 0
+    assert nums == [1]
+
+    nums = [3, 2, 2, 3]
+    assert Solution().removeElement(nums=nums, val=3) == 2
+    assert nums == [2, 2, 3, 3]
+
+    nums = [2, 2, 3, 3]
+    assert Solution().removeElement(nums=nums, val=3) == 2
+    assert nums == [2, 2, 3, 3]
+
+    nums = [3, 3, 3, 3]
+    assert Solution().removeElement(nums=nums, val=3) == 0
+    assert nums == [3, 3, 3, 3]
+
+    nums = [0, 1, 2, 2, 3, 0, 4, 2]
+    assert Solution().removeElement(nums=nums, val=2) == 5
+    assert nums[:5] == [0, 1, 4, 0, 3]

classic150/_003_26.py

@@ -0,0 +1,41 @@
+from typing import List
+
+
+class Solution:
+    def removeDuplicates(self, nums: List[int]) -> int:
+        index = cur = 0
+        while cur + 1 < len(nums):
+            # 找到一个与当前不相同的索引
+            while cur + 1 < len(nums) and nums[cur + 1] == nums[cur]:
+                cur = cur + 1
+            # 找到后，原地赋值，索引往后移动，元素个数加一
+            # 找不到的 case 表示后面几位一样，不需要操作，由外层 while 结束
+            if cur + 1 < len(nums):
+                nums[index + 1] = nums[cur + 1]
+                cur += 1
+                index += 1
+        return index + 1
+
+
+if __name__ == "__main__":
+    nums = [1, 1, 2]
+    assert Solution().removeDuplicates(nums=nums) == 2
+    assert nums[:2] == [1, 2]
+
+    nums = [0, 0, 1, 1, 1, 2, 2, 3, 3, 4]
+    assert Solution().removeDuplicates(nums=nums) == 5
+    assert nums[:5] == [0, 1, 2, 3, 4]
+
+    nums = [1]
+    assert Solution().removeDuplicates(nums=nums) == 1
+    assert nums[:1] == [1]
+
+    nums = [1, 1]
+    assert Solution().removeDuplicates(nums=nums) == 1
+    assert nums[:1] == [1]
+
+    nums = [1, 2, 3, 4]
+    assert Solution().removeDuplicates(nums=nums) == 4
+    assert nums[:4] == [1, 2, 3, 4]
+    # print(nums)
+    # assert 1 == 2

classic150/_005_169.py

@@ -0,0 +1,21 @@
+from typing import List
+
+
+class Solution:
+    def majorityElement(self, nums: List[int]) -> int:
+        win = nums[0]
+        count = 1
+        for num in nums[1:]:
+            if win == num:
+                count += 1
+            elif win != num:
+                count -= 1
+                if count < 0:
+                    win = num
+                    count = 1
+        return win
+
+
+if __name__ == "__main__":
+    assert Solution().majorityElement(nums=[3, 2, 3]) == 3
+    assert Solution().majorityElement(nums=[2, 2, 1, 1, 1, 2, 2]) == 2