Sync LeetCode submission Runtime - 0 ms (100.00%), Memory - 19.1 MB (7.21%)

Author: jimit105

0034-find-first-and-last-position-of-element-in-sorted-array/README.md

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+<p>Given an array of integers <code>nums</code> sorted in non-decreasing order, find the starting and ending position of a given <code>target</code> value.</p>
+
+<p>If <code>target</code> is not found in the array, return <code>[-1, -1]</code>.</p>
+
+<p>You must&nbsp;write an algorithm with&nbsp;<code>O(log n)</code> runtime complexity.</p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+<pre><strong>Input:</strong> nums = [5,7,7,8,8,10], target = 8
+<strong>Output:</strong> [3,4]
+</pre><p><strong class="example">Example 2:</strong></p>
+<pre><strong>Input:</strong> nums = [5,7,7,8,8,10], target = 6
+<strong>Output:</strong> [-1,-1]
+</pre><p><strong class="example">Example 3:</strong></p>
+<pre><strong>Input:</strong> nums = [], target = 0
+<strong>Output:</strong> [-1,-1]
+</pre>
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>0 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
+	<li><code>-10<sup>9</sup>&nbsp;&lt;= nums[i]&nbsp;&lt;= 10<sup>9</sup></code></li>
+	<li><code>nums</code> is a non-decreasing array.</li>
+	<li><code>-10<sup>9</sup>&nbsp;&lt;= target&nbsp;&lt;= 10<sup>9</sup></code></li>
+</ul>

0034-find-first-and-last-position-of-element-in-sorted-array/solution.py

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+# Approach: Binary Search
+
+# Time: O(log n)
+# Space: O(1)
+
+class Solution:
+    def searchRange(self, nums: List[int], target: int) -> List[int]:
+        lower_bound = self.findBound(nums, target, True)
+        if lower_bound == -1:
+            return [-1, -1]
+        
+        upper_bound = self.findBound(nums, target, False)
+
+        return [lower_bound, upper_bound]
+
+    def findBound(self, nums: List[int], target: int, isFirst: bool) -> int:
+        n = len(nums)
+        begin, end = 0, n - 1
+
+        while begin <= end:
+            mid = (begin + end) // 2
+
+            if nums[mid] == target:
+                if isFirst:
+                    # This means we found our lower bound.
+                    if mid == begin or nums[mid - 1] < target:
+                        return mid
+
+                    # Search on the left side for the bound.
+                    end = mid - 1
+
+                else:
+                    # This means we found our upper bound.
+                    if mid == end or nums[mid + 1] > target:
+                        return mid
+
+                    # Search on the right side for the bound.
+                    begin = mid + 1
+
+            elif nums[mid] > target:
+                end = mid - 1
+
+            else:
+                begin = mid + 1
+
+        return -1