solve: counting bits

Author: sounmind

counting-bits/evan.js

@@ -0,0 +1,25 @@
+/**
+ * @param {number} n
+ * @return {number[]}
+ */
+var countBits = function (n) {
+  const result = new Array(n + 1).fill(0);
+
+  for (let i = 1; i <= n; i++) {
+    /** The number of 1's in i divided by 2, except last bit of i */
+    const totalOnes = result[i >> 1];
+    const lastBit = i & 1;
+
+    result[i] = totalOnes + lastBit;
+  }
+
+  return result;
+};
+
+/**
+ * Time Complexity: O(n), where n is number input
+ * Reason: The algorithm processes each number from 1 to n exactly once.
+ *
+ * Space Complexity: O(n), where n is number input
+ * Reason: The algorithm uses an array of size n + 1
+ */