[Totschka] Week 2

climbing-stairs/Totschka.ts

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+// https://leetcode.com/problems/climbing-stairs/
+/**
+ * @SC `O(1)`
+ * @TC `O(n)`
+ */
+function climbStairs(n: number): number {
+  if (n <= 2) {
+    return n;
+  }
+
+  let prev1 = 1;
+  let prev2 = 2;
+
+  for (let i = 2; i < n; i++) {
+    let temp = prev1;
+    prev1 = prev2;
+    prev2 = temp + prev2;
+  }
+  return prev2;
+}

valid-anagram/Totschka.ts

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+// https://leetcode.com/problems/valid-anagram/
+
+/**
+ * @SC `O(N)`
+ * @TC `O(N)`
+ */
+namespace use_hashmap {
+  function isAnagram(s: string, t: string): boolean {
+    if (s.length !== t.length) {
+      return false;
+    }
+    const counter = {};
+    for (const char of s) {
+      counter[char] = (counter[char] || 0) + 1;
+    }
+    for (const char of t) {
+      if (!counter[char]) {
+        return false;
+      }
+      counter[char] = counter[char] - 1;
+    }
+    return true;
+  }
+}
+
+/**
+ * @SC `O(N)`
+ * @TC `O(Nlog(N))`
+ */
+namespace naive_approach {
+  function isAnagram(s: string, t: string): boolean {
+    return [...s].sort().join('') === [...t].sort().join('');
+  }
+}