[junzero741] WEEK 03 Solutions

number-of-1-bits/junzero741.ts

@@ -0,0 +1,13 @@
+// TC: O(log n)
+// SC: O(1)
+function hammingWeight(n: number): number {
+    const binary = n.toString(2);
+    let bits = 0;
+    for(let i = 0; i < binary.length; i++) {
+        if(binary[i] === '1') {
+            bits++;
+        }
+    }
+
+    return bits;
+};

valid-palindrome/junzero741.ts

@@ -0,0 +1,29 @@
+// TC: O(n)
+// SC: O(1)
+function isPalindrome(s: string): boolean {
+
+     let L = 0;
+     let R = s.length-1;
+
+    while(R > 0 && L < s.length - 1 && L <= R) {
+        if(!isAlphanumeric(s[L])) {
+            L++;
+            continue;
+        }
+        if(!isAlphanumeric(s[R])) {
+            R--;
+            continue;
+        }
+        if(s[L].toLowerCase() !==  s[R].toLowerCase()) {
+            return false;
+        }
+        L++;
+        R--;
+    }
+
+    return true;
+};
+
+function isAlphanumeric(str: string): boolean {
+    return /^[a-zA-Z0-9]+$/.test(str);
+}