Merge pull request neetcode-gh#379 from dipti95/TypeScript_Javascript…

…_solutions

twoSum and graphValidTree solutions

typescript/1-Two-Sum.ts

@@ -0,0 +1,11 @@
+function twoSum(nums: number[], target: number): number[] {
+ let hash: { [key: number]: number } = {}
+ for (let i = 0; i < nums.length; i++) {
+ let diff = target - nums[i]
+ if (diff in hash) {
+ return [hash[diff], i]
+ } else {
+ hash[nums[i]] = i
+ }
+ }
+}

typescript/261-Graph-Valid-Tree.ts

@@ -0,0 +1,42 @@
+interface Obj {
+ [key: number]: Array<number>
+}
+
+interface Visited {
+ [key: number]: boolean
+}
+
+function validTree(n: number, edges: number[][]): boolean {
+ if (n === 0) return true
+
+ let adjacent: Obj = {}
+ let visited: Visited = {}
+ for (let i = 0; i < n; i++) {
+ adjacent[i] = []
+ }
+
+ for (const val of edges) {
+ const [n1, n2] = val
+ adjacent[n1].push(n2)
+ adjacent[n2].push(n1)
+ }
+
+ return dfs(0, -1, visited, adjacent) && Object.keys(visited).length === n
+}
+
+function dfs(
+ node: number,
+ prevNode: number,
+ visited: Visited,
+ adjacent: Obj
+): boolean {
+ if (visited[node]) return false
+ visited[node] = true
+
+ for (const ele of adjacent[node]) {
+ if (ele === prevNode) continue
+ if (!dfs(ele, node, visited, adjacent)) return false
+ }
+
+ return true
+}