[reeseo3o] WEEK 03 solutions

combination-sum/reeseo3o.js

@@ -0,0 +1,20 @@
+const combinationSum = (candidates, target) => {
+  const result = [];
+
+  const backtrack = (startIndex, current, remaining) => {
+    if (remaining === 0) {
+      result.push([...current]);
+      return;
+    }
+    if (remaining < 0) return;
+
+    for (let i = startIndex; i < candidates.length; i++) {
+      current.push(candidates[i]);
+      backtrack(i, current, remaining - candidates[i]);
+      current.pop();
+    }
+  };
+
+  backtrack(0, [], target);
+  return result;
+};

number-of-1-bits/reeseo3o.js

@@ -0,0 +1 @@
+const hammingWeight = (n) => n.toString(2).split("").filter(b => b === "1").length;

valid-palindrome/reeseo3o.js

@@ -0,0 +1,5 @@
+const isPalindrome = (s) => {
+    const cleaned = s.toLowerCase().replace(/[^a-z0-9]/g, '');
+    const reversed = cleaned.split('').reverse().join('');
+    return cleaned === reversed;
+};