Add rob to Tree

Author: lewis617

Tree/BinarySearchTree.js

@@ -133,6 +133,27 @@ function BinarySearchTree() {
       }
     }
   };
+  /**
+   * 打家劫舍问题：房屋按二叉树来排列，
+   * 不允许在同一晚打劫相邻的两家，
+   * 求能打劫到的最大钱财数量。
+   */
+  this.rob = function () {
+    var dfs = function(node){
+      if(node === null){
+        return [null, null];
+      }
+      var left = dfs(node.left);
+      var right = dfs(node.right);
+      var res = [];
+      res[0] = left[1] + right[1] + node.key;
+      res[1] = Math.max(left[0], left[1]) + Math.max(right[0], right[1]);
+      return res;
+    };
+
+    var num = dfs(root);
+    return Math.max(num[0], num[1]);
+  };
 
   var minNode = function (node) {
     if (node) {

Tree/BinarySearchTree.test.js

@@ -17,6 +17,8 @@ test('BinarySearchTree', function () {
   expect(binarySearchTree.values('postOrderTraverse')).toEqual([3, 5, 9, 7, 13, 11]);
   expect(binarySearchTree.values('postOrderTraverseUnRec')).toEqual([3, 5, 9, 7, 13, 11]);
 
+  expect(binarySearchTree.rob()).toBe(27);
+
   expect(binarySearchTree.min()).toBe(3);
   expect(binarySearchTree.max()).toBe(13);
   expect(binarySearchTree.search(3)).toBeTruthy();