solve: missing number

Author: sounmind

missing-number/evan.js

@@ -0,0 +1,26 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var missingNumber = function (nums) {
+  const expectedSum = (nums.length * (nums.length + 1)) / 2;
+  const actualSum = nums.reduce((prev, curr) => prev + curr);
+
+  return expectedSum - actualSum;
+};
+
+/**
+ * Time Complexity: O(n)
+ * Reason:
+ * - Finding the maximum number in the array takes O(n) time.
+ * - Calculating the target sum takes O(1) time.
+ * - Iterating through the array to update the target number takes O(n) time.
+ * - Checking the condition and returning the result takes O(1) time.
+ * - Therefore, the overall time complexity is O(n).
+ *
+ * Space Complexity: O(1)
+ * Reason:
+ * - The algorithm uses a constant amount of extra space (variables like maxNumber, hasZero, targetNumber).
+ * - No additional space proportional to the input size is used.
+ * - Therefore, the overall space complexity is O(1).
+ */