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Author: chappdev2019

0893-all-nodes-distance-k-in-binary-tree/0893-all-nodes-distance-k-in-binary-tree.js

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+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val) {
+ *     this.val = val;
+ *     this.left = this.right = null;
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @param {TreeNode} target
+ * @param {number} k
+ * @return {number[]}
+ */
+var distanceK = function(root, target, k) {
+    if (!root) return [];
+
+    let map = new Map(); 
+    let parentMap = new Map(); 
+    let queue = [];
+    
+    queue.push(root);
+    map.set(root.val, 0);
+    parentMap.set(root, null);
+
+    while (queue.length > 0) {
+        let cur = queue.pop();
+        let level = map.get(cur.val);
+
+        if (cur.left) {
+            queue.push(cur.left);
+            map.set(cur.left.val, level + 1);
+            parentMap.set(cur.left, cur);
+        }
+
+        if (cur.right) {
+            queue.push(cur.right);
+            map.set(cur.right.val, level + 1);
+            parentMap.set(cur.right, cur);
+        }
+    }
+
+    let res = [];
+    let visited = new Set();
+    queue = [[target, 0]];
+    visited.add(target);
+
+    while (queue.length > 0) {
+        let [cur, distance] = queue.shift();
+
+        if (distance === k) {
+            res.push(cur.val);
+            continue;
+        }
+    
+        for (let neighbor of [cur.left, cur.right, parentMap.get(cur)]) {
+            if (neighbor && !visited.has(neighbor)) {
+                queue.push([neighbor, distance + 1]);
+                visited.add(neighbor);
+            }
+        }
+    }
+
+    return res;
+};