广度优先搜索 leetcode-993-cousins-in-binary-tree​​​​​​​

leetcode-993-cousins-in-binary-tree

题意：判断两个节点是否是相同深度且不同父亲（堂兄弟姐妹）

bfs，将节点和深度绑定为pair加入队列，记录目标节点的深度和父亲

遍历完之后判断即可

/**
 * 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:
    int d1=0,p1=0;
    int d2=0,p2=0;
    void bfs(TreeNode* root,int x, int y)
    {
        queue<pair<TreeNode*,int>> q;
        q.push({root,1});
        int d=1,p=1;
        while(!q.empty())
        {
            TreeNode* t = q.front().first;
            int dd = q.front().second;
            q.pop();
            if(t->left){
                if(t->left->val==x){
                    p1=t->val;
                    d1=dd+1;
                }
                if(t->left->val==y){
                    p2=t->val;
                    d2=dd+1;
                }
                q.push({t->left,dd+1});
            }
            if(t->right){
                if(t->right->val==x){
                    p1=t->val;
                    d1=dd+1;
                }
                if(t->right->val==y){
                    p2=t->val;
                    d2=dd+1;
                }
                q.push({t->right,dd+1});
            }
        }
    }
    bool isCousins(TreeNode* root, int x, int y) {
        bfs(root,x,y);
        if(d1==d2&&p1!=p2) return true;
        else return false;
    }
};