题解 | #二叉树的最大宽度#

/**
 * struct TreeNode {
 *	int val;
 *	struct TreeNode *left;
 *	struct TreeNode *right;
 *	TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 * };
 */
class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param root TreeNode类 
     * @return int整型
     */
    int widthOfBinaryTree(TreeNode* root) {
        if(root == NULL)
            return 0;
        queue<TreeNode*> qu;  //记录结点
        queue<int> order;   //记录序号
        qu.push(root);
        order.push(1);
        int maxwidth = 0,pos,first;
        while(!qu.empty()){
            int size = qu.size();
            for(int i = 0;i < size;++i){
                TreeNode *cur = qu.front();
                pos = order.front();
                if(i == 0)
                    first = pos;
                if(i == size - 1)
                    maxwidth = max(maxwidth,pos - first + 1);
                order.pop();
                qu.pop();
                if(cur->left){
                    qu.push(cur->left);
                    order.push(pos * 2);
                }
                if(cur->right){
                    qu.push(cur->right);
                    order.push(pos * 2 + 1);
                }
            }
        }
        return maxwidth;
    }
};