Create 1483-kth-ancestor-of-a-tree-node.js

Author: everthis

1483-kth-ancestor-of-a-tree-node.js

@@ -0,0 +1,41 @@
+/**
+ * @param {number} n
+ * @param {number[]} parent
+ */
+var TreeAncestor = function(n, parent) {
+    // initialize
+    this.P = Array.from({length: 20}, () => Array(n).fill(-1))
+    // 2^0
+    for(let i = 0; i < parent.length; i++){
+        this.P[0][i] = parent[i];
+    }
+
+    // 2^i
+    for(let i = 1; i < 20; i++){
+        for(let node = 0; node < parent.length; node++){
+            let nodep = this.P[i-1][node];
+            if(nodep != -1) this.P[i][node] = this.P[i-1][nodep];
+        }
+    }  
+};
+
+/** 
+ * @param {number} node 
+ * @param {number} k
+ * @return {number}
+ */
+TreeAncestor.prototype.getKthAncestor = function(node, k) {
+    for(let i = 0; i < 20; i++){
+        if(k & (1 << i)){
+            node = this.P[i][node];
+            if(node == -1) return -1;
+        }
+    }
+    return node; 
+};
+
+/** 
+ * Your TreeAncestor object will be instantiated and called as such:
+ * var obj = new TreeAncestor(n, parent)
+ * var param_1 = obj.getKthAncestor(node,k)
+ */