missing-number

Author: taewanseoul

missing-number/taewanseoul.ts

@@ -0,0 +1,20 @@
+/**
+ * 268. Missing Number
+ * Given an array nums containing n distinct numbers in the range [0, n], return the only number in the range that is missing from the array.
+ *
+ * https://leetcode.com/problems/missing-number/description/
+ */
+
+// O(n) time
+// O(1) space
+function missingNumber(nums: number[]): number {
+  const n = nums.length;
+  let total = (n * (n + 1)) / 2;
+
+  let sum = 0;
+  for (let i = 0; i < n; i++) {
+    sum += nums[i];
+  }
+
+  return total - sum;
+}