[Jeehay28] WEEK 14

binary-tree-level-order-traversal/Jeehay28.js

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+// ✅ Time Complexity: O(n), where n is the number of nodes in the tree
+// ✅ Space Complexity: O(n)
+
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {number[][]}
+ */
+var levelOrder = function (root) {
+  if (!root) return [];
+
+  let output = [];
+  let queue = [root];
+
+  while (queue.length > 0) {
+    let values = [];
+
+    const lengthQueue = queue.length;
+
+    for (let i = 0; i < lengthQueue; i++) {
+      const node = queue.shift();
+      values.push(node.val);
+      if (node.left) queue.push(node.left);
+      if (node.right) queue.push(node.right);
+    }
+    output.push(values);
+  }
+  return output;
+};
+

counting-bits/Jeehay28.js

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+// ✅ Time Complexity: O(n)
+// ✅ Space Complexity: O(n)
+
+/**
+ * @param {number} n
+ * @return {number[]}
+ */
+var countBits = function (n) {
+  // dp[i] = 1 + dp[i - MSB]
+  // MSB(Most Significant Bit)
+
+  let dp = new Array(n + 1).fill(0);
+  let msb = 1;
+
+  for (let i = 1; i <= n; i++) {
+    if (msb * 2 === i) {
+      msb = i;
+    }
+
+    dp[i] = 1 + dp[i - msb];
+  }
+
+  return dp;
+};
+
+// ✅ Time Complexity: O(n * logn)
+// ✅ Space Complexity: O(n)
+
+/**
+ * @param {number} n
+ * @return {number[]}
+ */
+// var countBits = function (n) {
+//   let result = [0];
+//   const count = (num) => {
+//     let cnt = 0;
+//     while (num !== 0) {
+//       cnt += num % 2;
+//       num = Math.floor(num / 2);
+//     }
+//     return cnt;
+//   };
+
+//   for (let i = 1; i <= n; i++) {
+//     const temp = count(i);
+//     result.push(temp);
+//   }
+
+//   return result;
+// };
+