Sync LeetCode submission Runtime - 0 ms (100.00%), Memory - 18.5 MB (77.72%)

Author: jimit105

0268-missing-number/README.md

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+<p>Given an array <code>nums</code> containing <code>n</code> distinct numbers in the range <code>[0, n]</code>, return <em>the only number in the range that is missing from the array.</em></p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">nums = [3,0,1]</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">2</span></p>
+
+<p><strong>Explanation:</strong></p>
+
+<p><code>n = 3</code> since there are 3 numbers, so all numbers are in the range <code>[0,3]</code>. 2 is the missing number in the range since it does not appear in <code>nums</code>.</p>
+</div>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">nums = [0,1]</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">2</span></p>
+
+<p><strong>Explanation:</strong></p>
+
+<p><code>n = 2</code> since there are 2 numbers, so all numbers are in the range <code>[0,2]</code>. 2 is the missing number in the range since it does not appear in <code>nums</code>.</p>
+</div>
+
+<p><strong class="example">Example 3:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">nums = [9,6,4,2,3,5,7,0,1]</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">8</span></p>
+
+<p><strong>Explanation:</strong></p>
+
+<p><code>n = 9</code> since there are 9 numbers, so all numbers are in the range <code>[0,9]</code>. 8 is the missing number in the range since it does not appear in <code>nums</code>.</p>
+</div>
+
+<div class="simple-translate-system-theme" id="simple-translate">
+<div>
+<div class="simple-translate-button isShow" style="background-image: url(&quot;moz-extension://8a9ffb6b-7e69-4e93-aae1-436a1448eff6/icons/512.png&quot;); height: 22px; width: 22px; top: 318px; left: 36px;">&nbsp;</div>
+
+<div class="simple-translate-panel " style="width: 300px; height: 200px; top: 0px; left: 0px; font-size: 13px;">
+<div class="simple-translate-result-wrapper" style="overflow: hidden;">
+<div class="simple-translate-move" draggable="true">&nbsp;</div>
+
+<div class="simple-translate-result-contents">
+<p class="simple-translate-result" dir="auto">&nbsp;</p>
+
+<p class="simple-translate-candidate" dir="auto">&nbsp;</p>
+</div>
+</div>
+</div>
+</div>
+</div>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>n == nums.length</code></li>
+	<li><code>1 &lt;= n &lt;= 10<sup>4</sup></code></li>
+	<li><code>0 &lt;= nums[i] &lt;= n</code></li>
+	<li>All the numbers of <code>nums</code> are <strong>unique</strong>.</li>
+</ul>
+
+<p>&nbsp;</p>
+<p><strong>Follow up:</strong> Could you implement a solution using only <code>O(1)</code> extra space complexity and <code>O(n)</code> runtime complexity?</p>

0268-missing-number/solution.py

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+# Approach 4: Math
+
+# Time: O(n)
+# Space: O(1)
+
+class Solution:
+    def missingNumber(self, nums: List[int]) -> int:
+        n = len(nums)
+        expected_sum = n * (n + 1) // 2
+        actual_sum = sum(nums)
+        return expected_sum - actual_sum