[leetcode.Tree]563. Binary Tree Tilt

Given a binary tree, return the tilt of the whole tree.

The tilt of a tree node is defined as the absolute difference between the sum of all left subtree node values and the sum of all right subtree node values. Null node has tilt 0.

The tilt of the whole tree is defined as the sum of all nodes’ tilt.

Example:
Input: 
         1
       /   \
      2     3
Output: 1
Explanation: 
Tilt of node 2 : 0
Tilt of node 3 : 0
Tilt of node 1 : |2-3| = 1
Tilt of binary tree : 0 + 0 + 1 = 1

Solution:

#define CATCH_CONFIG_MAIN
#include "catch.hpp"
#include <vector>
#include <stdlib.h>
using namespace std;
struct TreeNode {
     int val;
     TreeNode *left;
     TreeNode *right;
     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};

class Solution {
public:
    int tilt=0;
    int findTilt(TreeNode* root) {
        if (root==NULL) return 0;
        postOrder(root);
        return tilt;
    }

    int postOrder(TreeNode* root){
        if (root==NULL) return 0;
        int leftSum = postOrder(root->left);
        int rightSum = postOrder(root->right);
        tilt +=  abs(leftSum-rightSum);
        int result = leftSum + rightSum + root->val;
        return result;
    }
};

TEST_CASE("findTilt", "[findTilt"){
    TreeNode A = TreeNode(1);
    TreeNode B = TreeNode(2);
    TreeNode C = TreeNode(3);
    A.left = &B;
    A.right = &C;
    Solution so;

    REQUIRE(so.findTilt(&A) == 1);

}

需要文件：catch.hpp

➜  Tree g++ -std=c++11 563BinaryTreeTile.cpp
➜  Tree ./a.out
===============================================================================
All tests passed (1 assertion in 1 test case)