2: counting bits

Author: whewchews

counting-bits/whewchews.ts

@@ -0,0 +1,19 @@
+function countBits(n: number): number[] {
+  // SC: O(N)
+  const ans = Array(n + 1).fill(0);
+  // TC: O(N)
+  for (let i = 1; i <= n; i++) {
+    let k = i;
+
+    // TC: O(log N)
+    while (k > 0) {
+      ans[i] += k % 2;
+      k = Math.floor(k / 2);
+    }
+  }
+
+  return ans;
+}
+
+// TC: O(N log N)
+// SC: O(N)