662. Maximum Width of Binary Tree

Given a binary tree, write a function to get the maximum width of the
given tree. The width of a tree is the maximum width among all levels.
The binary tree has the same structure as a full binary tree, but some
nodes are null.

The width of one level is defined as the length between the end-nodes
(the leftmost and right most non-null nodes in the level, where the
null nodes between the end-nodes are also counted into the length
calculation.

/** * Definition for a binary tree node. * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:    /*creat the id number of each Tree Node*/    int creatNumTree(struct TreeNode *root,struct TreeNode *numRoot){        struct TreeNode * newNode = NULL;        if(root == NULL || numRoot == NULL){            return -1;        }        if(root->left){            newNode = (struct TreeNode *)malloc(sizeof(struct TreeNode ));            newNode->val = numRoot->val * 2;            newNode->left = NULL;            newNode->right = NULL;            numRoot->left = newNode;            creatNumTree(root->left,newNode);        }        if(root->right){            newNode = (struct TreeNode *)malloc(sizeof(struct TreeNode ));            newNode->val = numRoot->val * 2 + 1;            newNode->left = NULL;            newNode->right = NULL;            numRoot->right = newNode;            creatNumTree(root->right,newNode);        }        return 0;    }    int widthOfBinaryTree(TreeNode* root) {        struct TreeNode * newRoot = NULL;        queue< TreeNode* > qu;        int maxWidth = 1;                 if(root == NULL){            return 0;        }        newRoot = (struct TreeNode *)malloc(sizeof(struct TreeNode ));        newRoot->val = 1;        newRoot->left = NULL;        newRoot->right = NULL;        creatNumTree(root,newRoot);        /*level travel the tree,we will get the result*/        qu.push(newRoot);        while(!qu.empty()){            int level = qu.size();            int left = 0;            int right = 1;            TreeNode * node = NULL;            /*each node of this level*/            for(int i = 0;i<level;i++){                node = qu.front();                qu.pop();                if( i == 0){                    left = node->val;                }                if( i == level-1){                    right = node->val;                }                if(node->left){                    qu.push(node->left);                }                if(node->right){                    qu.push(node->right);                }            }            maxWidth = (right-left+1)>maxWidth?(right-left+1):maxWidth;        }        return maxWidth;    }};