二分法

CodingProgrammer · web-flow · commit 04602ca04fc2 · 2020-12-02T16:08:25.000+08:00
diff --git a/每日一题/34在排序数组中查找元素的第一个和最后一个位置.py b/每日一题/34在排序数组中查找元素的第一个和最后一个位置.py
@@ -0,0 +1,82 @@
+'''
+Descripttion: 34. 在排序数组中查找元素的第一个和最后一个位置
+version: 1
+Author: Jason
+Date: 2020-12-01 16:12:21
+LastEditors: Jason
+LastEditTime: 2020-12-02 16:07:03
+'''
+
+
+from typing import List
+import random
+
+
+def GenerateRandomList(number, size):
+    temp = list([0])
+    random_legth = random.randint(0, size)
+    current_length = 0
+    while current_length < random_legth:
+        temp.append(random.randint(1, number))
+        current_length += 1
+    return temp
+
+
+class Solution:
+    def searchRange(self, nums: List[int], target: int) -> List[int]:
+        length = len(nums)
+        if length < 1:
+            return [-1, -1]
+        left = 0
+        right = length - 1
+        first_index = -1
+        last_index = -1
+        while left <= right:
+            mid = left + ((right - left) >> 1)
+            if nums[mid] == target:
+                first_index = mid
+                break
+            elif nums[mid] > target:
+                right = mid - 1
+            else:
+                left = mid + 1
+
+        if first_index == -1:
+            return [-1, -1]
+        # 向后找最大位置
+        cur = first_index
+        while cur < length and nums[cur] == target:
+            last_index = cur
+            cur += 1
+        # 向前找最小位置
+        cur = first_index
+        while cur > -1 and nums[cur] == target:
+            first_index = cur
+            cur -= 1
+        return [first_index, last_index]
+
+    def searchRange2(self, nums: List[int], target: int) -> List[int]:
+        if target in nums:
+            first_index = nums.index(target)
+            last_index = nums[::-1].index(target)
+            if (first_index + last_index + 1) == len(nums):
+                return [first_index, first_index]
+            return [first_index, len(nums) - 1 - last_index]
+        return [-1, -1]
+
+
+s = Solution()
+for _ in range(10):
+    li = GenerateRandomList(20, 20)
+    index_random = random.randint(0, len(li) - 1)
+    times_random = random.randint(1, 5)
+    li.extend([li[index_random]] * times_random)
+    target = li[index_random]
+    li.sort()
+    res = s.searchRange(li, target)
+    res_stand = s.searchRange2(li, target)
+    if res != res_stand:
+        print(li)
+        print(target)
+        print("Wrong")
+print("Done")
