add: typescript solutions for LC-1,LC-217,LC-242

typescript/1-Two-Sum.ts

@@ -0,0 +1,11 @@
+function twoSum(nums: number[], target: number): number[] {
+  const map = new Map();
+
+  for (let i = 0; i < nums.length; i++) {
+    if (map.has(nums[i])) {
+      return [i, map.get(nums[i])];
+    } else {
+      map.set(target - nums[i], i);
+    }
+  }
+}

typescript/217-Contains-Duplicate.ts

@@ -0,0 +1,10 @@
+function containsDuplicate(nums: number[]): boolean {
+  const set = new Set();
+
+  for (let i = 0; i < nums.length; i++) {
+    if (set.has(nums[i])) return true;
+    else set.add(nums[i]);
+  }
+
+  return false;
+}

typescript/242-Valid-Anagrams.ts

@@ -0,0 +1,16 @@
+function isAnagram(s: string, t: string): boolean {
+  if (s.length !== t.length) return false;
+
+  const store = new Array(26).fill(0);
+
+  for (let i = 0; i < s.length; i++) {
+    store[s.charCodeAt(i) - 'a'.charCodeAt(0)]++;
+    store[t.charCodeAt(i) - 'a'.charCodeAt(0)]--;
+  }
+
+  for (let i = 0; i < store.length; i++) {
+    if (store[i] !== 0) return false;
+  }
+
+  return true;
+}